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xen/virtio: Enable restricted memory access using Xen grant mappings

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In order to support virtio in Xen guests add a config option XEN_VIRTIO
enabling the user to specify whether in all Xen guests virtio should
be able to access memory via Xen grant mappings only on the host side.

Also set PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS feature from the guest
initialization code on Arm and x86 if CONFIG_XEN_VIRTIO is enabled.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/1654197833-25362-5-git-send-email-olekstysh@gmail.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2022-06-02 22:23:49 +03:00
parent d6aca3504c
commit fa1f57421e
5 changed files with 25 additions and 0 deletions
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2
arch/arm/xen/enlighten.c
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@ -443,6 +443,8 @@ static int __init xen_guest_init(void)
if (!xen_domain()) if (!xen_domain())
return 0; return 0;
xen_set_restricted_virtio_memory_access();
if (!acpi_disabled) if (!acpi_disabled)
xen_acpi_guest_init(); xen_acpi_guest_init();
else else

2
arch/x86/xen/enlighten_hvm.c
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@ -195,6 +195,8 @@ static void __init xen_hvm_guest_init(void)
if (xen_pv_domain()) if (xen_pv_domain())
return; return;
xen_set_restricted_virtio_memory_access();
init_hvm_pv_info(); init_hvm_pv_info();
reserve_shared_info(); reserve_shared_info();

2
arch/x86/xen/enlighten_pv.c
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@ -109,6 +109,8 @@ static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc);
static void __init xen_pv_init_platform(void) static void __init xen_pv_init_platform(void)
{ {
xen_set_restricted_virtio_memory_access();
populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP)); populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info); set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info);

11
drivers/xen/Kconfig
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@ -339,4 +339,15 @@ config XEN_GRANT_DMA_OPS
bool bool
select DMA_OPS select DMA_OPS
config XEN_VIRTIO
bool "Xen virtio support"
depends on VIRTIO
select XEN_GRANT_DMA_OPS
help
Enable virtio support for running as Xen guest. Depending on the
guest type this will require special support on the backend side
(qemu or kernel, depending on the virtio device types used).
If in doubt, say n.
endmenu endmenu

8
include/xen/xen.h
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@ -52,6 +52,14 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
extern u64 xen_saved_max_mem_size; extern u64 xen_saved_max_mem_size;
#endif #endif
#include <linux/platform-feature.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);
}
#ifdef CONFIG_XEN_UNPOPULATED_ALLOC #ifdef CONFIG_XEN_UNPOPULATED_ALLOC
int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages); int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages);
void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages); void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages);