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SubjectRe: [PATCH V3 4/8] xen/virtio: Enable restricted memory access using Xen grant mappings
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On 31.05.22 00:00, Oleksandr Tyshchenko wrote:

Hello all.

> From: Juergen Gross <jgross@suse.com>
>
> 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>
> ---
> Changes V1 -> V2:
> - new patch, split required changes from commit:
> "[PATCH V1 3/6] xen/virtio: Add option to restrict memory access under Xen"
> - rework according to new platform_has() infrastructure
>
> Changes V2 -> V3:
> - add Stefano's R-b

May I please ask for the ack or comments for x86 side here?



> ---
> arch/arm/xen/enlighten.c | 2 ++
> arch/x86/xen/enlighten_hvm.c | 2 ++
> arch/x86/xen/enlighten_pv.c | 2 ++
> drivers/xen/Kconfig | 11 +++++++++++
> include/xen/xen.h | 8 ++++++++
> 5 files changed, 25 insertions(+)
>
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index 07eb69f..1f9c3ba 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -443,6 +443,8 @@ static int __init xen_guest_init(void)
> if (!xen_domain())
> return 0;
>
> + xen_set_restricted_virtio_memory_access();
> +
> if (!acpi_disabled)
> xen_acpi_guest_init();
> else
> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
> index 517a9d8..8b71b1d 100644
> --- a/arch/x86/xen/enlighten_hvm.c
> +++ b/arch/x86/xen/enlighten_hvm.c
> @@ -195,6 +195,8 @@ static void __init xen_hvm_guest_init(void)
> if (xen_pv_domain())
> return;
>
> + xen_set_restricted_virtio_memory_access();
> +
> init_hvm_pv_info();
>
> reserve_shared_info();
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index ca85d14..30d24fe 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -108,6 +108,8 @@ static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc);
>
> static void __init xen_pv_init_platform(void)
> {
> + xen_set_restricted_virtio_memory_access();
> +
> populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
>
> set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info);
> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index 313a9127..a7bd8ce 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -339,4 +339,15 @@ config XEN_GRANT_DMA_OPS
> bool
> 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
> diff --git a/include/xen/xen.h b/include/xen/xen.h
> index a99bab8..0780a81 100644
> --- a/include/xen/xen.h
> +++ b/include/xen/xen.h
> @@ -52,6 +52,14 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
> extern u64 xen_saved_max_mem_size;
> #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
> int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages);
> void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages);

--
Regards,

Oleksandr Tyshchenko

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