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virtio: replace restricted mem access flag with callback

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Instead of having a global flag to require restricted memory access
for all virtio devices, introduce a callback which can select that
requirement on a per-device basis.

For convenience add a common function returning always true, which can
be used for use cases like SEV.

Per default use a callback always returning false.

As the callback needs to be set in early init code already, add a
virtio anchor which is builtin in case virtio is enabled.

Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 guest using Xen
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20220622063838.8854-2-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2022-06-22 08:38:36 +02:00
parent 8441dac05e
commit a603002eea
9 changed files with 51 additions and 13 deletions
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4
arch/s390/mm/init.c
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@ -31,7 +31,6 @@
#include <linux/cma.h>
#include <linux/gfp.h>
#include <linux/dma-direct.h>
#include <linux/platform-feature.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/pgalloc.h>
@ -48,6 +47,7 @@
#include <asm/kasan.h>
#include <asm/dma-mapping.h>
#include <asm/uv.h>
#include <linux/virtio_anchor.h>
#include <linux/virtio_config.h>
pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(".bss..swapper_pg_dir");
@ -175,7 +175,7 @@ static void pv_init(void)
if (!is_prot_virt_guest())
return;
platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS);
virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
/* make sure bounce buffers are shared */
swiotlb_init(true, SWIOTLB_FORCE | SWIOTLB_VERBOSE);

4
arch/x86/mm/mem_encrypt_amd.c
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@ -20,8 +20,8 @@
#include <linux/bitops.h>
#include <linux/dma-mapping.h>
#include <linux/virtio_config.h>
#include <linux/virtio_anchor.h>
#include <linux/cc_platform.h>
#include <linux/platform-feature.h>
#include <asm/tlbflush.h>
#include <asm/fixmap.h>
@ -245,7 +245,7 @@ void __init sev_setup_arch(void)
swiotlb_adjust_size(size);
/* Set restricted memory access for virtio. */
platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS);
virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
}
static unsigned long pg_level_to_pfn(int level, pte_t *kpte, pgprot_t *ret_prot)

4
drivers/virtio/Kconfig
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@ -1,6 +1,10 @@
# SPDX-License-Identifier: GPL-2.0-only
config VIRTIO_ANCHOR
bool
config VIRTIO
tristate
select VIRTIO_ANCHOR
help
This option is selected by any driver which implements the virtio
bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG

1
drivers/virtio/Makefile
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@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
obj-$(CONFIG_VIRTIO_ANCHOR) += virtio_anchor.o
obj-$(CONFIG_VIRTIO_PCI_LIB) += virtio_pci_modern_dev.o
obj-$(CONFIG_VIRTIO_PCI_LIB_LEGACY) += virtio_pci_legacy_dev.o
obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o

4
drivers/virtio/virtio.c
View File

@ -2,10 +2,10 @@
#include <linux/virtio.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.h>
#include <linux/virtio_anchor.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/of.h>
#include <linux/platform-feature.h>
#include <uapi/linux/virtio_ids.h>
/* Unique numbering for virtio devices. */
@ -174,7 +174,7 @@ static int virtio_features_ok(struct virtio_device *dev)
might_sleep();
if (platform_has(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS)) {
if (virtio_check_mem_acc_cb(dev)) {
if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
dev_warn(&dev->dev,
"device must provide VIRTIO_F_VERSION_1\n");

18
drivers/virtio/virtio_anchor.c Normal file
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@ -0,0 +1,18 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/virtio.h>
#include <linux/virtio_anchor.h>
bool virtio_require_restricted_mem_acc(struct virtio_device *dev)
{
return true;
}
EXPORT_SYMBOL_GPL(virtio_require_restricted_mem_acc);
static bool virtio_no_restricted_mem_acc(struct virtio_device *dev)
{
return false;
}
bool (*virtio_check_mem_acc_cb)(struct virtio_device *dev) =
virtio_no_restricted_mem_acc;
EXPORT_SYMBOL_GPL(virtio_check_mem_acc_cb);

6
include/linux/platform-feature.h
View File

@ -6,11 +6,7 @@
#include <asm/platform-feature.h>
/* The platform features are starting with the architecture specific ones. */
/* Used to enable platform specific DMA handling for virtio devices. */
#define PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS (0 + PLATFORM_ARCH_FEAT_N)
#define PLATFORM_FEAT_N (1 + PLATFORM_ARCH_FEAT_N)
#define PLATFORM_FEAT_N (0 + PLATFORM_ARCH_FEAT_N)
void platform_set(unsigned int feature);
void platform_clear(unsigned int feature);

19
include/linux/virtio_anchor.h Normal file
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@ -0,0 +1,19 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VIRTIO_ANCHOR_H
#define _LINUX_VIRTIO_ANCHOR_H
#ifdef CONFIG_VIRTIO_ANCHOR
struct virtio_device;
bool virtio_require_restricted_mem_acc(struct virtio_device *dev);
extern bool (*virtio_check_mem_acc_cb)(struct virtio_device *dev);
static inline void virtio_set_mem_acc_cb(bool (*func)(struct virtio_device *))
{
virtio_check_mem_acc_cb = func;
}
#else
#define virtio_set_mem_acc_cb(func) do { } while (0)
#endif
#endif /* _LINUX_VIRTIO_ANCHOR_H */

4
include/xen/xen.h
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@ -52,12 +52,12 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
extern u64 xen_saved_max_mem_size;
#endif
#include <linux/platform-feature.h>
#include <linux/virtio_anchor.h>
static inline void xen_set_restricted_virtio_memory_access(void)
{
if (IS_ENABLED(CONFIG_XEN_VIRTIO) && xen_domain())
platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS);
virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
}
#ifdef CONFIG_XEN_UNPOPULATED_ALLOC