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Merge branch kvm-arm64/eager-page-splitting into kvmarm/next

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* kvm-arm64/eager-page-splitting:
  : Eager Page Splitting, courtesy of Ricardo Koller.
  :
  : Dirty logging performance is dominated by the cost of splitting
  : hugepages to PTE granularity. On systems that mere mortals can get their
  : hands on, each fault incurs the cost of a full break-before-make
  : pattern, wherein the broadcast invalidation and ensuing serialization
  : significantly increases fault latency.
  :
  : The goal of eager page splitting is to move the cost of hugepage
  : splitting out of the stage-2 fault path and instead into the ioctls
  : responsible for managing the dirty log:
  :
  :  - If manual protection is enabled for the VM, hugepage splitting
  :    happens in the KVM_CLEAR_DIRTY_LOG ioctl. This is desirable as it
  :    provides userspace granular control over hugepage splitting.
  :
  :  - Otherwise, if userspace relies on the legacy dirty log behavior
  :    (clear on collection), hugepage splitting is done at the moment dirty
  :    logging is enabled for a particular memslot.
  :
  : Support for eager page splitting requires explicit opt-in from
  : userspace, which is realized through the
  : KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE capability.
  arm64: kvm: avoid overflow in integer division
  KVM: arm64: Use local TLBI on permission relaxation
  KVM: arm64: Split huge pages during KVM_CLEAR_DIRTY_LOG
  KVM: arm64: Open-code kvm_mmu_write_protect_pt_masked()
  KVM: arm64: Split huge pages when dirty logging is enabled
  KVM: arm64: Add kvm_uninit_stage2_mmu()
  KVM: arm64: Refactor kvm_arch_commit_memory_region()
  KVM: arm64: Add kvm_pgtable_stage2_split()
  KVM: arm64: Add KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE
  KVM: arm64: Export kvm_are_all_memslots_empty()
  KVM: arm64: Add helper for creating unlinked stage2 subtrees
  KVM: arm64: Add KVM_PGTABLE_WALK flags for skipping CMOs and BBM TLBIs
  KVM: arm64: Rename free_removed to free_unlinked

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2023-06-15 13:02:11 +00:00
commit 83510396c0
15 changed files with 613 additions and 58 deletions
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27
Documentation/virt/kvm/api.rst
View File

@ -8445,6 +8445,33 @@ structure.
When getting the Modified Change Topology Report value, the attr->addr
must point to a byte where the value will be stored or retrieved from.
8.40 KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE
---------------------------------------
:Capability: KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE
:Architectures: arm64
:Type: vm
:Parameters: arg[0] is the new split chunk size.
:Returns: 0 on success, -EINVAL if any memslot was already created.
This capability sets the chunk size used in Eager Page Splitting.
Eager Page Splitting improves the performance of dirty-logging (used
in live migrations) when guest memory is backed by huge-pages. It
avoids splitting huge-pages (into PAGE_SIZE pages) on fault, by doing
it eagerly when enabling dirty logging (with the
KVM_MEM_LOG_DIRTY_PAGES flag for a memory region), or when using
KVM_CLEAR_DIRTY_LOG.
The chunk size specifies how many pages to break at a time, using a
single allocation for each chunk. Bigger the chunk size, more pages
need to be allocated ahead of time.
The chunk size needs to be a valid block size. The list of acceptable
block sizes is exposed in KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES as a
64-bit bitmap (each bit describing a block size). The default value is
0, to disable the eager page splitting.
9. Known KVM API problems
=========================

4
arch/arm64/include/asm/kvm_asm.h
View File

@ -68,6 +68,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa_nsh,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid,
__KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context,
__KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff,
@ -225,6 +226,9 @@ extern void __kvm_flush_vm_context(void);
extern void __kvm_flush_cpu_context(struct kvm_s2_mmu *mmu);
extern void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu, phys_addr_t ipa,
int level);
extern void __kvm_tlb_flush_vmid_ipa_nsh(struct kvm_s2_mmu *mmu,
phys_addr_t ipa,
int level);
extern void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu);
extern void __kvm_timer_set_cntvoff(u64 cntvoff);

15
arch/arm64/include/asm/kvm_host.h
View File

@ -159,6 +159,21 @@ struct kvm_s2_mmu {
/* The last vcpu id that ran on each physical CPU */
int __percpu *last_vcpu_ran;
#define KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT 0
/*
* Memory cache used to split
* KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE worth of huge pages. It
* is used to allocate stage2 page tables while splitting huge
* pages. The choice of KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE
* influences both the capacity of the split page cache, and
* how often KVM reschedules. Be wary of raising CHUNK_SIZE
* too high.
*
* Protected by kvm->slots_lock.
*/
struct kvm_mmu_memory_cache split_page_cache;
uint64_t split_page_chunk_size;
struct kvm_arch *arch;
};

1
arch/arm64/include/asm/kvm_mmu.h
View File

@ -172,6 +172,7 @@ void __init free_hyp_pgds(void);
void stage2_unmap_vm(struct kvm *kvm);
int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long type);
void kvm_uninit_stage2_mmu(struct kvm *kvm);
void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
phys_addr_t pa, unsigned long size, bool writable);

79
arch/arm64/include/asm/kvm_pgtable.h
View File

@ -92,6 +92,24 @@ static inline bool kvm_level_supports_block_mapping(u32 level)
return level >= KVM_PGTABLE_MIN_BLOCK_LEVEL;
}
static inline u32 kvm_supported_block_sizes(void)
{
u32 level = KVM_PGTABLE_MIN_BLOCK_LEVEL;
u32 r = 0;
for (; level < KVM_PGTABLE_MAX_LEVELS; level++)
r |= BIT(kvm_granule_shift(level));
return r;
}
static inline bool kvm_is_block_size_supported(u64 size)
{
bool is_power_of_two = IS_ALIGNED(size, size);
return is_power_of_two && (size & kvm_supported_block_sizes());
}
/**
* struct kvm_pgtable_mm_ops - Memory management callbacks.
* @zalloc_page: Allocate a single zeroed memory page.
@ -104,7 +122,7 @@ static inline bool kvm_level_supports_block_mapping(u32 level)
* allocation is physically contiguous.
* @free_pages_exact: Free an exact number of memory pages previously
* allocated by zalloc_pages_exact.
* @free_removed_table: Free a removed paging structure by unlinking and
* @free_unlinked_table: Free an unlinked paging structure by unlinking and
* dropping references.
* @get_page: Increment the refcount on a page.
* @put_page: Decrement the refcount on a page. When the
@ -124,7 +142,7 @@ struct kvm_pgtable_mm_ops {
void* (*zalloc_page)(void *arg);
void* (*zalloc_pages_exact)(size_t size);
void (*free_pages_exact)(void *addr, size_t size);
void (*free_removed_table)(void *addr, u32 level);
void (*free_unlinked_table)(void *addr, u32 level);
void (*get_page)(void *addr);
void (*put_page)(void *addr);
int (*page_count)(void *addr);
@ -195,6 +213,12 @@ typedef bool (*kvm_pgtable_force_pte_cb_t)(u64 addr, u64 end,
* with other software walkers.
* @KVM_PGTABLE_WALK_HANDLE_FAULT: Indicates the page-table walk was
* invoked from a fault handler.
* @KVM_PGTABLE_WALK_SKIP_BBM_TLBI: Visit and update table entries
* without Break-before-make's
* TLB invalidation.
* @KVM_PGTABLE_WALK_SKIP_CMO: Visit and update table entries
* without Cache maintenance
* operations required.
*/
enum kvm_pgtable_walk_flags {
KVM_PGTABLE_WALK_LEAF = BIT(0),
@ -202,6 +226,8 @@ enum kvm_pgtable_walk_flags {
KVM_PGTABLE_WALK_TABLE_POST = BIT(2),
KVM_PGTABLE_WALK_SHARED = BIT(3),
KVM_PGTABLE_WALK_HANDLE_FAULT = BIT(4),
KVM_PGTABLE_WALK_SKIP_BBM_TLBI = BIT(5),
KVM_PGTABLE_WALK_SKIP_CMO = BIT(6),
};
struct kvm_pgtable_visit_ctx {
@ -441,7 +467,7 @@ int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
/**
* kvm_pgtable_stage2_free_removed() - Free a removed stage-2 paging structure.
* kvm_pgtable_stage2_free_unlinked() - Free an unlinked stage-2 paging structure.
* @mm_ops: Memory management callbacks.
* @pgtable: Unlinked stage-2 paging structure to be freed.
* @level: Level of the stage-2 paging structure to be freed.
@ -449,7 +475,33 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
* The page-table is assumed to be unreachable by any hardware walkers prior to
* freeing and therefore no TLB invalidation is performed.
*/
void kvm_pgtable_stage2_free_removed(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level);
void kvm_pgtable_stage2_free_unlinked(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level);
/**
* kvm_pgtable_stage2_create_unlinked() - Create an unlinked stage-2 paging structure.
* @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
* @phys: Physical address of the memory to map.
* @level: Starting level of the stage-2 paging structure to be created.
* @prot: Permissions and attributes for the mapping.
* @mc: Cache of pre-allocated and zeroed memory from which to allocate
* page-table pages.
* @force_pte: Force mappings to PAGE_SIZE granularity.
*
* Returns an unlinked page-table tree. This new page-table tree is
* not reachable (i.e., it is unlinked) from the root pgd and it's
* therefore unreachableby the hardware page-table walker. No TLB
* invalidation or CMOs are performed.
*
* If device attributes are not explicitly requested in @prot, then the
* mapping will be normal, cacheable.
*
* Return: The fully populated (unlinked) stage-2 paging structure, or
* an ERR_PTR(error) on failure.
*/
kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt,
u64 phys, u32 level,
enum kvm_pgtable_prot prot,
void *mc, bool force_pte);
/**
* kvm_pgtable_stage2_map() - Install a mapping in a guest stage-2 page-table.
@ -620,6 +672,25 @@ bool kvm_pgtable_stage2_is_young(struct kvm_pgtable *pgt, u64 addr);
*/
int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size);
/**
* kvm_pgtable_stage2_split() - Split a range of huge pages into leaf PTEs pointing
* to PAGE_SIZE guest pages.
* @pgt: Page-table structure initialised by kvm_pgtable_stage2_init().
* @addr: Intermediate physical address from which to split.
* @size: Size of the range.
* @mc: Cache of pre-allocated and zeroed memory from which to allocate
* page-table pages.
*
* The function tries to split any level 1 or 2 entry that overlaps
* with the input range (given by @addr and @size).
*
* Return: 0 on success, negative error code on failure. Note that
* kvm_pgtable_stage2_split() is best effort: it tries to break as many
* blocks in the input range as allowed by @mc_capacity.
*/
int kvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size,
struct kvm_mmu_memory_cache *mc);
/**
* kvm_pgtable_walk() - Walk a page-table.
* @pgt: Page-table structure initialised by kvm_pgtable_*_init().

28
arch/arm64/kvm/arm.c
View File

@ -65,6 +65,7 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
struct kvm_enable_cap *cap)
{
int r;
u64 new_cap;
if (cap->flags)
return -EINVAL;
@ -89,6 +90,24 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
r = 0;
set_bit(KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED, &kvm->arch.flags);
break;
case KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE:
new_cap = cap->args[0];
mutex_lock(&kvm->slots_lock);
/*
* To keep things simple, allow changing the chunk
* size only when no memory slots have been created.
*/
if (!kvm_are_all_memslots_empty(kvm)) {
r = -EINVAL;
} else if (new_cap && !kvm_is_block_size_supported(new_cap)) {
r = -EINVAL;
} else {
r = 0;
kvm->arch.mmu.split_page_chunk_size = new_cap;
}
mutex_unlock(&kvm->slots_lock);
break;
default:
r = -EINVAL;
break;
@ -302,6 +321,15 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_ARM_PTRAUTH_GENERIC:
r = system_has_full_ptr_auth();
break;
case KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE:
if (kvm)
r = kvm->arch.mmu.split_page_chunk_size;
else
r = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT;
break;
case KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES:
r = kvm_supported_block_sizes();
break;
default:
r = 0;
}

10
arch/arm64/kvm/hyp/nvhe/hyp-main.c
View File

@ -125,6 +125,15 @@ static void handle___kvm_tlb_flush_vmid_ipa(struct kvm_cpu_context *host_ctxt)
__kvm_tlb_flush_vmid_ipa(kern_hyp_va(mmu), ipa, level);
}
static void handle___kvm_tlb_flush_vmid_ipa_nsh(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
DECLARE_REG(phys_addr_t, ipa, host_ctxt, 2);
DECLARE_REG(int, level, host_ctxt, 3);
__kvm_tlb_flush_vmid_ipa_nsh(kern_hyp_va(mmu), ipa, level);
}
static void handle___kvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
@ -315,6 +324,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__kvm_vcpu_run),
HANDLE_FUNC(__kvm_flush_vm_context),
HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa),
HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa_nsh),
HANDLE_FUNC(__kvm_tlb_flush_vmid),
HANDLE_FUNC(__kvm_flush_cpu_context),
HANDLE_FUNC(__kvm_timer_set_cntvoff),

6
arch/arm64/kvm/hyp/nvhe/mem_protect.c
View File

@ -91,9 +91,9 @@ static void host_s2_put_page(void *addr)
hyp_put_page(&host_s2_pool, addr);
}
static void host_s2_free_removed_table(void *addr, u32 level)
static void host_s2_free_unlinked_table(void *addr, u32 level)
{
kvm_pgtable_stage2_free_removed(&host_mmu.mm_ops, addr, level);
kvm_pgtable_stage2_free_unlinked(&host_mmu.mm_ops, addr, level);
}
static int prepare_s2_pool(void *pgt_pool_base)
@ -110,7 +110,7 @@ static int prepare_s2_pool(void *pgt_pool_base)
host_mmu.mm_ops = (struct kvm_pgtable_mm_ops) {
.zalloc_pages_exact = host_s2_zalloc_pages_exact,
.zalloc_page = host_s2_zalloc_page,
.free_removed_table = host_s2_free_removed_table,
.free_unlinked_table = host_s2_free_unlinked_table,
.phys_to_virt = hyp_phys_to_virt,
.virt_to_phys = hyp_virt_to_phys,
.page_count = hyp_page_count,

52
arch/arm64/kvm/hyp/nvhe/tlb.c
View File

@ -130,6 +130,58 @@ void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu,
__tlb_switch_to_host(&cxt);
}
void __kvm_tlb_flush_vmid_ipa_nsh(struct kvm_s2_mmu *mmu,
phys_addr_t ipa, int level)
{
struct tlb_inv_context cxt;
/* Switch to requested VMID */
__tlb_switch_to_guest(mmu, &cxt, true);
/*
* We could do so much better if we had the VA as well.
* Instead, we invalidate Stage-2 for this IPA, and the
* whole of Stage-1. Weep...
*/
ipa >>= 12;
__tlbi_level(ipas2e1, ipa, level);
/*
* We have to ensure completion of the invalidation at Stage-2,
* since a table walk on another CPU could refill a TLB with a
* complete (S1 + S2) walk based on the old Stage-2 mapping if
* the Stage-1 invalidation happened first.
*/
dsb(nsh);
__tlbi(vmalle1);
dsb(nsh);
isb();
/*
* If the host is running at EL1 and we have a VPIPT I-cache,
* then we must perform I-cache maintenance at EL2 in order for
* it to have an effect on the guest. Since the guest cannot hit
* I-cache lines allocated with a different VMID, we don't need
* to worry about junk out of guest reset (we nuke the I-cache on
* VMID rollover), but we do need to be careful when remapping
* executable pages for the same guest. This can happen when KSM
* takes a CoW fault on an executable page, copies the page into
* a page that was previously mapped in the guest and then needs
* to invalidate the guest view of the I-cache for that page
* from EL1. To solve this, we invalidate the entire I-cache when
* unmapping a page from a guest if we have a VPIPT I-cache but
* the host is running at EL1. As above, we could do better if
* we had the VA.
*
* The moral of this story is: if you have a VPIPT I-cache, then
* you should be running with VHE enabled.
*/
if (icache_is_vpipt())
icache_inval_all_pou();
__tlb_switch_to_host(&cxt);
}
void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu)
{
struct tlb_inv_context cxt;

201
arch/arm64/kvm/hyp/pgtable.c
View File

@ -63,6 +63,16 @@ struct kvm_pgtable_walk_data {
const u64 end;
};
static bool kvm_pgtable_walk_skip_bbm_tlbi(const struct kvm_pgtable_visit_ctx *ctx)
{
return unlikely(ctx->flags & KVM_PGTABLE_WALK_SKIP_BBM_TLBI);
}
static bool kvm_pgtable_walk_skip_cmo(const struct kvm_pgtable_visit_ctx *ctx)
{
return unlikely(ctx->flags & KVM_PGTABLE_WALK_SKIP_CMO);
}
static bool kvm_phys_is_valid(u64 phys)
{
return phys < BIT(id_aa64mmfr0_parange_to_phys_shift(ID_AA64MMFR0_EL1_PARANGE_MAX));
@ -743,14 +753,17 @@ static bool stage2_try_break_pte(const struct kvm_pgtable_visit_ctx *ctx,
if (!stage2_try_set_pte(ctx, KVM_INVALID_PTE_LOCKED))
return false;
/*
* Perform the appropriate TLB invalidation based on the evicted pte
* value (if any).
*/
if (kvm_pte_table(ctx->old, ctx->level))
kvm_call_hyp(__kvm_tlb_flush_vmid, mmu);
else if (kvm_pte_valid(ctx->old))
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr, ctx->level);
if (!kvm_pgtable_walk_skip_bbm_tlbi(ctx)) {
/*
* Perform the appropriate TLB invalidation based on the
* evicted pte value (if any).
*/
if (kvm_pte_table(ctx->old, ctx->level))
kvm_call_hyp(__kvm_tlb_flush_vmid, mmu);
else if (kvm_pte_valid(ctx->old))
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu,
ctx->addr, ctx->level);
}
if (stage2_pte_is_counted(ctx->old))
mm_ops->put_page(ctx->ptep);
@ -857,11 +870,13 @@ static int stage2_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx,
return -EAGAIN;
/* Perform CMOs before installation of the guest stage-2 PTE */
if (mm_ops->dcache_clean_inval_poc && stage2_pte_cacheable(pgt, new))
if (!kvm_pgtable_walk_skip_cmo(ctx) && mm_ops->dcache_clean_inval_poc &&
stage2_pte_cacheable(pgt, new))
mm_ops->dcache_clean_inval_poc(kvm_pte_follow(new, mm_ops),
granule);
granule);
if (mm_ops->icache_inval_pou && stage2_pte_executable(new))
if (!kvm_pgtable_walk_skip_cmo(ctx) && mm_ops->icache_inval_pou &&
stage2_pte_executable(new))
mm_ops->icache_inval_pou(kvm_pte_follow(new, mm_ops), granule);
stage2_make_pte(ctx, new);
@ -883,7 +898,7 @@ static int stage2_map_walk_table_pre(const struct kvm_pgtable_visit_ctx *ctx,
if (ret)
return ret;
mm_ops->free_removed_table(childp, ctx->level);
mm_ops->free_unlinked_table(childp, ctx->level);
return 0;
}
@ -928,7 +943,7 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx,
* The TABLE_PRE callback runs for table entries on the way down, looking
* for table entries which we could conceivably replace with a block entry
* for this mapping. If it finds one it replaces the entry and calls
* kvm_pgtable_mm_ops::free_removed_table() to tear down the detached table.
* kvm_pgtable_mm_ops::free_unlinked_table() to tear down the detached table.
*
* Otherwise, the LEAF callback performs the mapping at the existing leaves
* instead.
@ -1197,7 +1212,7 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
KVM_PGTABLE_WALK_HANDLE_FAULT |
KVM_PGTABLE_WALK_SHARED);
if (!ret)
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, pgt->mmu, addr, level);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa_nsh, pgt->mmu, addr, level);
return ret;
}
@ -1230,6 +1245,162 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
return kvm_pgtable_walk(pgt, addr, size, &walker);
}
kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt,
u64 phys, u32 level,
enum kvm_pgtable_prot prot,
void *mc, bool force_pte)
{
struct stage2_map_data map_data = {
.phys = phys,
.mmu = pgt->mmu,
.memcache = mc,
.force_pte = force_pte,
};
struct kvm_pgtable_walker walker = {
.cb = stage2_map_walker,
.flags = KVM_PGTABLE_WALK_LEAF |
KVM_PGTABLE_WALK_SKIP_BBM_TLBI |
KVM_PGTABLE_WALK_SKIP_CMO,
.arg = &map_data,
};
/*
* The input address (.addr) is irrelevant for walking an
* unlinked table. Construct an ambiguous IA range to map
* kvm_granule_size(level) worth of memory.
*/
struct kvm_pgtable_walk_data data = {
.walker = &walker,
.addr = 0,
.end = kvm_granule_size(level),
};
struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
kvm_pte_t *pgtable;
int ret;
if (!IS_ALIGNED(phys, kvm_granule_size(level)))
return ERR_PTR(-EINVAL);
ret = stage2_set_prot_attr(pgt, prot, &map_data.attr);
if (ret)
return ERR_PTR(ret);
pgtable = mm_ops->zalloc_page(mc);
if (!pgtable)
return ERR_PTR(-ENOMEM);
ret = __kvm_pgtable_walk(&data, mm_ops, (kvm_pteref_t)pgtable,
level + 1);
if (ret) {
kvm_pgtable_stage2_free_unlinked(mm_ops, pgtable, level);
mm_ops->put_page(pgtable);
return ERR_PTR(ret);
}
return pgtable;
}
/*
* Get the number of page-tables needed to replace a block with a
* fully populated tree up to the PTE entries. Note that @level is
* interpreted as in "level @level entry".
*/
static int stage2_block_get_nr_page_tables(u32 level)
{
switch (level) {
case 1:
return PTRS_PER_PTE + 1;
case 2:
return 1;
case 3:
return 0;
default:
WARN_ON_ONCE(level < KVM_PGTABLE_MIN_BLOCK_LEVEL ||
level >= KVM_PGTABLE_MAX_LEVELS);
return -EINVAL;
};
}
static int stage2_split_walker(const struct kvm_pgtable_visit_ctx *ctx,
enum kvm_pgtable_walk_flags visit)
{
struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops;
struct kvm_mmu_memory_cache *mc = ctx->arg;
struct kvm_s2_mmu *mmu;
kvm_pte_t pte = ctx->old, new, *childp;
enum kvm_pgtable_prot prot;
u32 level = ctx->level;
bool force_pte;
int nr_pages;
u64 phys;
/* No huge-pages exist at the last level */
if (level == KVM_PGTABLE_MAX_LEVELS - 1)
return 0;
/* We only split valid block mappings */
if (!kvm_pte_valid(pte))
return 0;
nr_pages = stage2_block_get_nr_page_tables(level);
if (nr_pages < 0)
return nr_pages;
if (mc->nobjs >= nr_pages) {
/* Build a tree mapped down to the PTE granularity. */
force_pte = true;
} else {
/*
* Don't force PTEs, so create_unlinked() below does
* not populate the tree up to the PTE level. The
* consequence is that the call will require a single
* page of level 2 entries at level 1, or a single
* page of PTEs at level 2. If we are at level 1, the
* PTEs will be created recursively.
*/
force_pte = false;
nr_pages = 1;
}
if (mc->nobjs < nr_pages)
return -ENOMEM;
mmu = container_of(mc, struct kvm_s2_mmu, split_page_cache);
phys = kvm_pte_to_phys(pte);
prot = kvm_pgtable_stage2_pte_prot(pte);
childp = kvm_pgtable_stage2_create_unlinked(mmu->pgt, phys,
level, prot, mc, force_pte);
if (IS_ERR(childp))
return PTR_ERR(childp);
if (!stage2_try_break_pte(ctx, mmu)) {
kvm_pgtable_stage2_free_unlinked(mm_ops, childp, level);
mm_ops->put_page(childp);
return -EAGAIN;
}
/*
* Note, the contents of the page table are guaranteed to be made
* visible before the new PTE is assigned because stage2_make_pte()
* writes the PTE using smp_store_release().
*/
new = kvm_init_table_pte(childp, mm_ops);
stage2_make_pte(ctx, new);
dsb(ishst);
return 0;
}
int kvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size,
struct kvm_mmu_memory_cache *mc)
{
struct kvm_pgtable_walker walker = {
.cb = stage2_split_walker,
.flags = KVM_PGTABLE_WALK_LEAF,
.arg = mc,
};
return kvm_pgtable_walk(pgt, addr, size, &walker);
}
int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
struct kvm_pgtable_mm_ops *mm_ops,
@ -1299,7 +1470,7 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
pgt->pgd = NULL;
}
void kvm_pgtable_stage2_free_removed(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level)
void kvm_pgtable_stage2_free_unlinked(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level)
{
kvm_pteref_t ptep = (kvm_pteref_t)pgtable;
struct kvm_pgtable_walker walker = {

32
arch/arm64/kvm/hyp/vhe/tlb.c
View File

@ -111,6 +111,38 @@ void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu,
__tlb_switch_to_host(&cxt);
}
void __kvm_tlb_flush_vmid_ipa_nsh(struct kvm_s2_mmu *mmu,
phys_addr_t ipa, int level)
{
struct tlb_inv_context cxt;
dsb(nshst);
/* Switch to requested VMID */
__tlb_switch_to_guest(mmu, &cxt);
/*
* We could do so much better if we had the VA as well.
* Instead, we invalidate Stage-2 for this IPA, and the
* whole of Stage-1. Weep...
*/
ipa >>= 12;
__tlbi_level(ipas2e1, ipa, level);
/*
* We have to ensure completion of the invalidation at Stage-2,
* since a table walk on another CPU could refill a TLB with a
* complete (S1 + S2) walk based on the old Stage-2 mapping if
* the Stage-1 invalidation happened first.
*/
dsb(nsh);
__tlbi(vmalle1);
dsb(nsh);
isb();
__tlb_switch_to_host(&cxt);
}
void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu)
{
struct tlb_inv_context cxt;

209
arch/arm64/kvm/mmu.c
View File

@ -31,14 +31,21 @@ static phys_addr_t __ro_after_init hyp_idmap_vector;
static unsigned long __ro_after_init io_map_base;
static phys_addr_t stage2_range_addr_end(phys_addr_t addr, phys_addr_t end)
static phys_addr_t __stage2_range_addr_end(phys_addr_t addr, phys_addr_t end,
phys_addr_t size)
{
phys_addr_t size = kvm_granule_size(KVM_PGTABLE_MIN_BLOCK_LEVEL);
phys_addr_t boundary = ALIGN_DOWN(addr + size, size);
return (boundary - 1 < end - 1) ? boundary : end;
}
static phys_addr_t stage2_range_addr_end(phys_addr_t addr, phys_addr_t end)
{
phys_addr_t size = kvm_granule_size(KVM_PGTABLE_MIN_BLOCK_LEVEL);
return __stage2_range_addr_end(addr, end, size);
}
/*
* Release kvm_mmu_lock periodically if the memory region is large. Otherwise,
* we may see kernel panics with CONFIG_DETECT_HUNG_TASK,
@ -75,6 +82,79 @@ static int stage2_apply_range(struct kvm_s2_mmu *mmu, phys_addr_t addr,
#define stage2_apply_range_resched(mmu, addr, end, fn) \
stage2_apply_range(mmu, addr, end, fn, true)
/*
* Get the maximum number of page-tables pages needed to split a range
* of blocks into PAGE_SIZE PTEs. It assumes the range is already
* mapped at level 2, or at level 1 if allowed.
*/
static int kvm_mmu_split_nr_page_tables(u64 range)
{
int n = 0;
if (KVM_PGTABLE_MIN_BLOCK_LEVEL < 2)
n += DIV_ROUND_UP(range, PUD_SIZE);
n += DIV_ROUND_UP(range, PMD_SIZE);
return n;
}
static bool need_split_memcache_topup_or_resched(struct kvm *kvm)
{
struct kvm_mmu_memory_cache *cache;
u64 chunk_size, min;
if (need_resched() || rwlock_needbreak(&kvm->mmu_lock))
return true;
chunk_size = kvm->arch.mmu.split_page_chunk_size;
min = kvm_mmu_split_nr_page_tables(chunk_size);
cache = &kvm->arch.mmu.split_page_cache;
return kvm_mmu_memory_cache_nr_free_objects(cache) < min;
}
static int kvm_mmu_split_huge_pages(struct kvm *kvm, phys_addr_t addr,
phys_addr_t end)
{
struct kvm_mmu_memory_cache *cache;
struct kvm_pgtable *pgt;
int ret, cache_capacity;
u64 next, chunk_size;
lockdep_assert_held_write(&kvm->mmu_lock);
chunk_size = kvm->arch.mmu.split_page_chunk_size;
cache_capacity = kvm_mmu_split_nr_page_tables(chunk_size);
if (chunk_size == 0)
return 0;
cache = &kvm->arch.mmu.split_page_cache;
do {
if (need_split_memcache_topup_or_resched(kvm)) {
write_unlock(&kvm->mmu_lock);
cond_resched();
/* Eager page splitting is best-effort. */
ret = __kvm_mmu_topup_memory_cache(cache,
cache_capacity,
cache_capacity);
write_lock(&kvm->mmu_lock);
if (ret)
break;
}
pgt = kvm->arch.mmu.pgt;
if (!pgt)
return -EINVAL;
next = __stage2_range_addr_end(addr, end, chunk_size);
ret = kvm_pgtable_stage2_split(pgt, addr, next - addr, cache);
if (ret)
break;
} while (addr = next, addr != end);
return ret;
}
static bool memslot_is_logging(struct kvm_memory_slot *memslot)
{
return memslot->dirty_bitmap && !(memslot->flags & KVM_MEM_READONLY);
@ -131,21 +211,21 @@ static void kvm_s2_free_pages_exact(void *virt, size_t size)
static struct kvm_pgtable_mm_ops kvm_s2_mm_ops;
static void stage2_free_removed_table_rcu_cb(struct rcu_head *head)
static void stage2_free_unlinked_table_rcu_cb(struct rcu_head *head)
{
struct page *page = container_of(head, struct page, rcu_head);
void *pgtable = page_to_virt(page);
u32 level = page_private(page);
kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, pgtable, level);
kvm_pgtable_stage2_free_unlinked(&kvm_s2_mm_ops, pgtable, level);
}
static void stage2_free_removed_table(void *addr, u32 level)
static void stage2_free_unlinked_table(void *addr, u32 level)
{
struct page *page = virt_to_page(addr);
set_page_private(page, (unsigned long)level);
call_rcu(&page->rcu_head, stage2_free_removed_table_rcu_cb);
call_rcu(&page->rcu_head, stage2_free_unlinked_table_rcu_cb);
}
static void kvm_host_get_page(void *addr)
@ -701,7 +781,7 @@ static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
.zalloc_page = stage2_memcache_zalloc_page,
.zalloc_pages_exact = kvm_s2_zalloc_pages_exact,
.free_pages_exact = kvm_s2_free_pages_exact,
.free_removed_table = stage2_free_removed_table,
.free_unlinked_table = stage2_free_unlinked_table,
.get_page = kvm_host_get_page,
.put_page = kvm_s2_put_page,
.page_count = kvm_host_page_count,
@ -775,6 +855,10 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
for_each_possible_cpu(cpu)
*per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1;
/* The eager page splitting is disabled by default */
mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT;
mmu->split_page_cache.gfp_zero = __GFP_ZERO;
mmu->pgt = pgt;
mmu->pgd_phys = __pa(pgt->pgd);
return 0;
@ -786,6 +870,12 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
return err;
}
void kvm_uninit_stage2_mmu(struct kvm *kvm)
{
kvm_free_stage2_pgd(&kvm->arch.mmu);
kvm_mmu_free_memory_cache(&kvm->arch.mmu.split_page_cache);
}
static void stage2_unmap_memslot(struct kvm *kvm,
struct kvm_memory_slot *memslot)
{
@ -989,17 +1079,45 @@ static void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
}
/**
* kvm_mmu_write_protect_pt_masked() - write protect dirty pages
* kvm_mmu_split_memory_region() - split the stage 2 blocks into PAGE_SIZE
* pages for memory slot
* @kvm: The KVM pointer
* @slot: The memory slot to split
*
* Acquires kvm->mmu_lock. Called with kvm->slots_lock mutex acquired,
* serializing operations for VM memory regions.
*/
static void kvm_mmu_split_memory_region(struct kvm *kvm, int slot)
{
struct kvm_memslots *slots;
struct kvm_memory_slot *memslot;
phys_addr_t start, end;
lockdep_assert_held(&kvm->slots_lock);
slots = kvm_memslots(kvm);
memslot = id_to_memslot(slots, slot);
start = memslot->base_gfn << PAGE_SHIFT;
end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
write_lock(&kvm->mmu_lock);
kvm_mmu_split_huge_pages(kvm, start, end);
write_unlock(&kvm->mmu_lock);
}
/*
* kvm_arch_mmu_enable_log_dirty_pt_masked() - enable dirty logging for selected pages.
* @kvm: The KVM pointer
* @slot: The memory slot associated with mask
* @gfn_offset: The gfn offset in memory slot
* @mask: The mask of dirty pages at offset 'gfn_offset' in this memory
* slot to be write protected
* @mask: The mask of pages at offset 'gfn_offset' in this memory
* slot to enable dirty logging on
*
* Walks bits set in mask write protects the associated pte's. Caller must
* acquire kvm_mmu_lock.
* Writes protect selected pages to enable dirty logging, and then
* splits them to PAGE_SIZE. Caller must acquire kvm->mmu_lock.
*/
static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
struct kvm_memory_slot *slot,
gfn_t gfn_offset, unsigned long mask)
{
@ -1007,21 +1125,20 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
phys_addr_t start = (base_gfn + __ffs(mask)) << PAGE_SHIFT;
phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
stage2_wp_range(&kvm->arch.mmu, start, end);
}
lockdep_assert_held_write(&kvm->mmu_lock);
/*
* kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected
* dirty pages.
*
* It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to
* enable dirty logging for them.
*/
void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
struct kvm_memory_slot *slot,
gfn_t gfn_offset, unsigned long mask)
{
kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
stage2_wp_range(&kvm->arch.mmu, start, end);
/*
* Eager-splitting is done when manual-protect is set. We
* also check for initially-all-set because we can avoid
* eager-splitting if initially-all-set is false.
* Initially-all-set equal false implies that huge-pages were
* already split when enabling dirty logging: no need to do it
* again.
*/
if (kvm_dirty_log_manual_protect_and_init_set(kvm))
kvm_mmu_split_huge_pages(kvm, start, end);
}
static void kvm_send_hwpoison_signal(unsigned long address, short lsb)
@ -1790,20 +1907,42 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
const struct kvm_memory_slot *new,
enum kvm_mr_change change)
{
bool log_dirty_pages = new && new->flags & KVM_MEM_LOG_DIRTY_PAGES;
/*
* At this point memslot has been committed and there is an
* allocated dirty_bitmap[], dirty pages will be tracked while the
* memory slot is write protected.
*/
if (change != KVM_MR_DELETE && new->flags & KVM_MEM_LOG_DIRTY_PAGES) {
if (log_dirty_pages) {
if (change == KVM_MR_DELETE)
return;
/*
* If we're with initial-all-set, we don't need to write
* protect any pages because they're all reported as dirty.
* Huge pages and normal pages will be write protect gradually.
* Huge and normal pages are write-protected and split
* on either of these two cases:
*
* 1. with initial-all-set: gradually with CLEAR ioctls,
*/
if (!kvm_dirty_log_manual_protect_and_init_set(kvm)) {
kvm_mmu_wp_memory_region(kvm, new->id);
}
if (kvm_dirty_log_manual_protect_and_init_set(kvm))
return;
/*
* or
* 2. without initial-all-set: all in one shot when
* enabling dirty logging.
*/
kvm_mmu_wp_memory_region(kvm, new->id);
kvm_mmu_split_memory_region(kvm, new->id);
} else {
/*
* Free any leftovers from the eager page splitting cache. Do
* this when deleting, moving, disabling dirty logging, or
* creating the memslot (a nop). Doing it for deletes makes
* sure we don't leak memory, and there's no need to keep the
* cache around for any of the other cases.
*/
kvm_mmu_free_memory_cache(&kvm->arch.mmu.split_page_cache);
}
}
@ -1877,7 +2016,7 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
void kvm_arch_flush_shadow_all(struct kvm *kvm)
{
kvm_free_stage2_pgd(&kvm->arch.mmu);
kvm_uninit_stage2_mmu(kvm);
}
void kvm_arch_flush_shadow_memslot(struct kvm *kvm,

2
include/linux/kvm_host.h
View File

@ -991,6 +991,8 @@ static inline bool kvm_memslots_empty(struct kvm_memslots *slots)
return RB_EMPTY_ROOT(&slots->gfn_tree);
}
bool kvm_are_all_memslots_empty(struct kvm *kvm);
#define kvm_for_each_memslot(memslot, bkt, slots) \
hash_for_each(slots->id_hash, bkt, memslot, id_node[slots->node_idx]) \
if (WARN_ON_ONCE(!memslot->npages)) { \

2
include/uapi/linux/kvm.h
View File

@ -1190,6 +1190,8 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP 225
#define KVM_CAP_PMU_EVENT_MASKED_EVENTS 226
#define KVM_CAP_COUNTER_OFFSET 227
#define KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE 228
#define KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES 229
#ifdef KVM_CAP_IRQ_ROUTING

3
virt/kvm/kvm_main.c
View File

@ -4602,7 +4602,7 @@ int __attribute__((weak)) kvm_vm_ioctl_enable_cap(struct kvm *kvm,
return -EINVAL;
}
static bool kvm_are_all_memslots_empty(struct kvm *kvm)
bool kvm_are_all_memslots_empty(struct kvm *kvm)
{
int i;
@ -4615,6 +4615,7 @@ static bool kvm_are_all_memslots_empty(struct kvm *kvm)
return true;
}
EXPORT_SYMBOL_GPL(kvm_are_all_memslots_empty);
static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
struct kvm_enable_cap *cap)