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KVM: guest_memfd: Provide "struct page" as output from kvm_gmem_get_pfn()

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Provide the "struct page" associated with a guest_memfd pfn as an output
from __kvm_gmem_get_pfn() so that KVM guest page fault handlers can
directly put the page instead of having to rely on
kvm_pfn_to_refcounted_page().

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-47-seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-10-10 11:23:48 -07:00 committed by Paolo Bonzini
parent 4af18dc6a9
commit 1fbee5b01a
4 changed files with 17 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/kvm/mmu/mmu.c
View File

@ -4407,7 +4407,7 @@ static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu,
}
r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn,
&max_order);
&fault->refcounted_page, &max_order);
if (r) {
kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
return r;

10
arch/x86/kvm/svm/sev.c
View File

@ -3849,6 +3849,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
if (VALID_PAGE(svm->sev_es.snp_vmsa_gpa)) {
gfn_t gfn = gpa_to_gfn(svm->sev_es.snp_vmsa_gpa);
struct kvm_memory_slot *slot;
struct page *page;
kvm_pfn_t pfn;
slot = gfn_to_memslot(vcpu->kvm, gfn);
@ -3859,7 +3860,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
* The new VMSA will be private memory guest memory, so
* retrieve the PFN from the gmem backend.
*/
if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, NULL))
if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, &page, NULL))
return -EINVAL;
/*
@ -3888,7 +3889,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
* changes then care should be taken to ensure
* svm->sev_es.vmsa is pinned through some other means.
*/
kvm_release_pfn_clean(pfn);
kvm_release_page_clean(page);
}
/*
@ -4688,6 +4689,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code)
struct kvm_memory_slot *slot;
struct kvm *kvm = vcpu->kvm;
int order, rmp_level, ret;
struct page *page;
bool assigned;
kvm_pfn_t pfn;
gfn_t gfn;
@ -4714,7 +4716,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code)
return;
}
ret = kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, &order);
ret = kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, &page, &order);
if (ret) {
pr_warn_ratelimited("SEV: Unexpected RMP fault, no backing page for private GPA 0x%llx\n",
gpa);
@ -4772,7 +4774,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code)
out:
trace_kvm_rmp_fault(vcpu, gpa, pfn, error_code, rmp_level, ret);
out_no_trace:
put_page(pfn_to_page(pfn));
kvm_release_page_unused(page);
}
static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end)

6
include/linux/kvm_host.h
View File

@ -2487,11 +2487,13 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
#ifdef CONFIG_KVM_PRIVATE_MEM
int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
gfn_t gfn, kvm_pfn_t *pfn, int *max_order);
gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
int *max_order);
#else
static inline int kvm_gmem_get_pfn(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn,
kvm_pfn_t *pfn, int *max_order)
kvm_pfn_t *pfn, struct page **page,
int *max_order)
{
KVM_BUG_ON(1, kvm);
return -EIO;

8
virt/kvm/guest_memfd.c
View File

@ -594,7 +594,8 @@ static struct folio *__kvm_gmem_get_pfn(struct file *file,
}
int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
int *max_order)
{
pgoff_t index = kvm_gmem_get_index(slot, gfn);
struct file *file = kvm_gmem_get_file(slot);
@ -615,7 +616,10 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio);
folio_unlock(folio);
if (r < 0)
if (!r)
*page = folio_file_page(folio, index);
else
folio_put(folio);
out: