[PATCH v2 0/2] x86/sev: Generalize sev_setup_arch()

[PATCH v2 0/2] x86/sev: Generalize sev_setup_arch()

[Alexander Shishkin]

Hi,

Since previous version [0], I added 2/2, which is a minor cleanup.

The main intention of this is to move sev_setup_arch() to mem_encrypt.c
to reflect the fact that it's not SEV-specific, but covers TDX as well,
although unintentionally.

While looking at it, I also noticed that mem_encrypt_amd.c still
includes virtio_config.h, which was needed for the code that since got
moved to a different place (and even there doesn't require the include
any more).

[0] https://lore.kernel.org/all/20230530121728.28854-1-alexander.shishkin@linux.intel.com/

Alexander Shishkin (2):
  x86/sev: Move sev_setup_arch() to mem_encrypt.c
  x86/sev: Drop unneeded include

 arch/x86/include/asm/mem_encrypt.h | 11 +++++++--
 arch/x86/kernel/setup.c            |  2 +-
 arch/x86/mm/mem_encrypt.c          | 34 ++++++++++++++++++++++++++++
 arch/x86/mm/mem_encrypt_amd.c      | 36 ------------------------------
 4 files changed, 44 insertions(+), 39 deletions(-)

-- 
2.39.2

[PATCH v2 1/2] x86/sev: Move sev_setup_arch() to mem_encrypt.c

[Alexander Shishkin]

Since commit 4d96f9109109b ("x86/sev: Replace occurrences of
sev_active() with cc_platform_has()"), the SWIOTLB bounce buffer size
adjustment and restricted virtio memory setting also inadvertently apply
to TDX: the code is using cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) as
a gatekeeping condition, which is also true for TDX, and this is also what
we want.

To reflect this, move the corresponding code to generic mem_encrypt.c.
No functional changes intended.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
 arch/x86/include/asm/mem_encrypt.h | 11 ++++++++--
 arch/x86/kernel/setup.c            |  2 +-
 arch/x86/mm/mem_encrypt.c          | 34 +++++++++++++++++++++++++++++
 arch/x86/mm/mem_encrypt_amd.c      | 35 ------------------------------
 4 files changed, 44 insertions(+), 38 deletions(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index b7126701574c..4283063c1e1c 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -37,7 +37,6 @@ void __init sme_map_bootdata(char *real_mode_data);
 void __init sme_unmap_bootdata(char *real_mode_data);
 
 void __init sme_early_init(void);
-void __init sev_setup_arch(void);
 
 void __init sme_encrypt_kernel(struct boot_params *bp);
 void __init sme_enable(struct boot_params *bp);
@@ -67,7 +66,6 @@ static inline void __init sme_map_bootdata(char *real_mode_data) { }
 static inline void __init sme_unmap_bootdata(char *real_mode_data) { }
 
 static inline void __init sme_early_init(void) { }
-static inline void __init sev_setup_arch(void) { }
 
 static inline void __init sme_encrypt_kernel(struct boot_params *bp) { }
 static inline void __init sme_enable(struct boot_params *bp) { }
@@ -92,6 +90,15 @@ void __init mem_encrypt_init(void);
 
 void add_encrypt_protection_map(void);
 
+#ifdef CONFIG_X86_MEM_ENCRYPT
+
+void __init mem_encrypt_setup_arch(void);
+
+#else	/* !CONFIG_X86_MEM_ENCRYPT */
+
+static inline void __init mem_encrypt_setup_arch(void) { }
+
+#endif	/* CONFIG_X86_MEM_ENCRYPT */
 /*
  * The __sme_pa() and __sme_pa_nodebug() macros are meant for use when
  * writing to or comparing values from the cr3 register.  Having the
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 16babff771bd..e2aa1d5b37a9 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1121,7 +1121,7 @@ void __init setup_arch(char **cmdline_p)
 	 * Needs to run after memblock setup because it needs the physical
 	 * memory size.
 	 */
-	sev_setup_arch();
+	mem_encrypt_setup_arch();
 
 	efi_fake_memmap();
 	efi_find_mirror();
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 9f27e14e185f..c290c55b632b 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -12,6 +12,7 @@
 #include <linux/swiotlb.h>
 #include <linux/cc_platform.h>
 #include <linux/mem_encrypt.h>
+#include <linux/virtio_anchor.h>
 
 /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
 bool force_dma_unencrypted(struct device *dev)
@@ -86,3 +87,36 @@ void __init mem_encrypt_init(void)
 
 	print_mem_encrypt_feature_info();
 }
+
+void __init mem_encrypt_setup_arch(void)
+{
+	phys_addr_t total_mem = memblock_phys_mem_size();
+	unsigned long size;
+
+	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
+		return;
+
+	/*
+	 * For SEV and TDX, all DMA has to occur via shared/unencrypted pages.
+	 * Kernel uses SWIOTLB to make this happen without changing device
+	 * drivers. However, depending on the workload being run, the
+	 * default 64MB of SWIOTLB may not be enough and SWIOTLB may
+	 * run out of buffers for DMA, resulting in I/O errors and/or
+	 * performance degradation especially with high I/O workloads.
+	 *
+	 * Adjust the default size of SWIOTLB using a percentage of guest
+	 * memory for SWIOTLB buffers. Also, as the SWIOTLB bounce buffer
+	 * memory is allocated from low memory, ensure that the adjusted size
+	 * is within the limits of low available memory.
+	 *
+	 * The percentage of guest memory used here for SWIOTLB buffers
+	 * is more of an approximation of the static adjustment which
+	 * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
+	 */
+	size = total_mem * 6 / 100;
+	size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
+	swiotlb_adjust_size(size);
+
+	/* Set restricted memory access for virtio. */
+	virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+}
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index e0b51c09109f..b1edeb8642b8 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -20,7 +20,6 @@
 #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 <asm/tlbflush.h>
@@ -215,40 +214,6 @@ void __init sme_map_bootdata(char *real_mode_data)
 	__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, true);
 }
 
-void __init sev_setup_arch(void)
-{
-	phys_addr_t total_mem = memblock_phys_mem_size();
-	unsigned long size;
-
-	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
-		return;
-
-	/*
-	 * For SEV, all DMA has to occur via shared/unencrypted pages.
-	 * SEV uses SWIOTLB to make this happen without changing device
-	 * drivers. However, depending on the workload being run, the
-	 * default 64MB of SWIOTLB may not be enough and SWIOTLB may
-	 * run out of buffers for DMA, resulting in I/O errors and/or
-	 * performance degradation especially with high I/O workloads.
-	 *
-	 * Adjust the default size of SWIOTLB for SEV guests using
-	 * a percentage of guest memory for SWIOTLB buffers.
-	 * Also, as the SWIOTLB bounce buffer memory is allocated
-	 * from low memory, ensure that the adjusted size is within
-	 * the limits of low available memory.
-	 *
-	 * The percentage of guest memory used here for SWIOTLB buffers
-	 * is more of an approximation of the static adjustment which
-	 * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
-	 */
-	size = total_mem * 6 / 100;
-	size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
-	swiotlb_adjust_size(size);
-
-	/* Set restricted memory access for virtio. */
-	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)
 {
 	unsigned long pfn = 0;
-- 
2.39.2

Re: [PATCH v2 1/2] x86/sev: Move sev_setup_arch() to mem_encrypt.c

[Tom Lendacky]

On 6/9/23 12:12, Alexander Shishkin wrote:
> Since commit 4d96f9109109b ("x86/sev: Replace occurrences of
> sev_active() with cc_platform_has()"), the SWIOTLB bounce buffer size
> adjustment and restricted virtio memory setting also inadvertently apply
> to TDX: the code is using cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) as
> a gatekeeping condition, which is also true for TDX, and this is also what
> we want.
> 
> To reflect this, move the corresponding code to generic mem_encrypt.c.
> No functional changes intended.
> 
> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> ---
>   arch/x86/include/asm/mem_encrypt.h | 11 ++++++++--
>   arch/x86/kernel/setup.c            |  2 +-
>   arch/x86/mm/mem_encrypt.c          | 34 +++++++++++++++++++++++++++++
>   arch/x86/mm/mem_encrypt_amd.c      | 35 ------------------------------
>   4 files changed, 44 insertions(+), 38 deletions(-)
> 
> diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
> index b7126701574c..4283063c1e1c 100644
> --- a/arch/x86/include/asm/mem_encrypt.h
> +++ b/arch/x86/include/asm/mem_encrypt.h
> @@ -37,7 +37,6 @@ void __init sme_map_bootdata(char *real_mode_data);
>   void __init sme_unmap_bootdata(char *real_mode_data);
>   
>   void __init sme_early_init(void);
> -void __init sev_setup_arch(void);
>   
>   void __init sme_encrypt_kernel(struct boot_params *bp);
>   void __init sme_enable(struct boot_params *bp);
> @@ -67,7 +66,6 @@ static inline void __init sme_map_bootdata(char *real_mode_data) { }
>   static inline void __init sme_unmap_bootdata(char *real_mode_data) { }
>   
>   static inline void __init sme_early_init(void) { }
> -static inline void __init sev_setup_arch(void) { }
>   
>   static inline void __init sme_encrypt_kernel(struct boot_params *bp) { }
>   static inline void __init sme_enable(struct boot_params *bp) { }
> @@ -92,6 +90,15 @@ void __init mem_encrypt_init(void);
>   
>   void add_encrypt_protection_map(void);
>   
> +#ifdef CONFIG_X86_MEM_ENCRYPT
> +
> +void __init mem_encrypt_setup_arch(void);
> +
> +#else	/* !CONFIG_X86_MEM_ENCRYPT */
> +
> +static inline void __init mem_encrypt_setup_arch(void) { }
> +
> +#endif	/* CONFIG_X86_MEM_ENCRYPT */

Commit 0a9567ac5e6a ("x86/mem_encrypt: Unbreak the AMD_MEM_ENCRYPT=n 
build") added a #ifdef for CONFIG_X86_MEM_ENCRYPT near the top of the 
file, it would be better to rebase and put these up with the 
mem_encrypt_init() definitions.

Otherwise, no objections.

Thanks,
Tom

>   /*
>    * The __sme_pa() and __sme_pa_nodebug() macros are meant for use when
>    * writing to or comparing values from the cr3 register.  Having the
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 16babff771bd..e2aa1d5b37a9 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1121,7 +1121,7 @@ void __init setup_arch(char **cmdline_p)
>   	 * Needs to run after memblock setup because it needs the physical
>   	 * memory size.
>   	 */
> -	sev_setup_arch();
> +	mem_encrypt_setup_arch();
>   
>   	efi_fake_memmap();
>   	efi_find_mirror();
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 9f27e14e185f..c290c55b632b 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -12,6 +12,7 @@
>   #include <linux/swiotlb.h>
>   #include <linux/cc_platform.h>
>   #include <linux/mem_encrypt.h>
> +#include <linux/virtio_anchor.h>
>   
>   /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
>   bool force_dma_unencrypted(struct device *dev)
> @@ -86,3 +87,36 @@ void __init mem_encrypt_init(void)
>   
>   	print_mem_encrypt_feature_info();
>   }
> +
> +void __init mem_encrypt_setup_arch(void)
> +{
> +	phys_addr_t total_mem = memblock_phys_mem_size();
> +	unsigned long size;
> +
> +	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
> +		return;
> +
> +	/*
> +	 * For SEV and TDX, all DMA has to occur via shared/unencrypted pages.
> +	 * Kernel uses SWIOTLB to make this happen without changing device
> +	 * drivers. However, depending on the workload being run, the
> +	 * default 64MB of SWIOTLB may not be enough and SWIOTLB may
> +	 * run out of buffers for DMA, resulting in I/O errors and/or
> +	 * performance degradation especially with high I/O workloads.
> +	 *
> +	 * Adjust the default size of SWIOTLB using a percentage of guest
> +	 * memory for SWIOTLB buffers. Also, as the SWIOTLB bounce buffer
> +	 * memory is allocated from low memory, ensure that the adjusted size
> +	 * is within the limits of low available memory.
> +	 *
> +	 * The percentage of guest memory used here for SWIOTLB buffers
> +	 * is more of an approximation of the static adjustment which
> +	 * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
> +	 */
> +	size = total_mem * 6 / 100;
> +	size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
> +	swiotlb_adjust_size(size);
> +
> +	/* Set restricted memory access for virtio. */
> +	virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
> +}
> diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
> index e0b51c09109f..b1edeb8642b8 100644
> --- a/arch/x86/mm/mem_encrypt_amd.c
> +++ b/arch/x86/mm/mem_encrypt_amd.c
> @@ -20,7 +20,6 @@
>   #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 <asm/tlbflush.h>
> @@ -215,40 +214,6 @@ void __init sme_map_bootdata(char *real_mode_data)
>   	__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, true);
>   }
>   
> -void __init sev_setup_arch(void)
> -{
> -	phys_addr_t total_mem = memblock_phys_mem_size();
> -	unsigned long size;
> -
> -	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
> -		return;
> -
> -	/*
> -	 * For SEV, all DMA has to occur via shared/unencrypted pages.
> -	 * SEV uses SWIOTLB to make this happen without changing device
> -	 * drivers. However, depending on the workload being run, the
> -	 * default 64MB of SWIOTLB may not be enough and SWIOTLB may
> -	 * run out of buffers for DMA, resulting in I/O errors and/or
> -	 * performance degradation especially with high I/O workloads.
> -	 *
> -	 * Adjust the default size of SWIOTLB for SEV guests using
> -	 * a percentage of guest memory for SWIOTLB buffers.
> -	 * Also, as the SWIOTLB bounce buffer memory is allocated
> -	 * from low memory, ensure that the adjusted size is within
> -	 * the limits of low available memory.
> -	 *
> -	 * The percentage of guest memory used here for SWIOTLB buffers
> -	 * is more of an approximation of the static adjustment which
> -	 * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
> -	 */
> -	size = total_mem * 6 / 100;
> -	size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
> -	swiotlb_adjust_size(size);
> -
> -	/* Set restricted memory access for virtio. */
> -	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)
>   {
>   	unsigned long pfn = 0;

[PATCH v2 2/2] x86/sev: Drop unneeded include

[Alexander Shishkin]

Commit 20f07a044a76 ("x86/sev: Move common memory encryption code to
mem_encrypt.c") forgot to remove the include of virtio_config.h from
mem_encrypt_amd.c when it moved the related code to mem_encrypt.c (from
where this include subsequently got removed by a later commit).

Remove it now. No functional changes.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
 arch/x86/mm/mem_encrypt_amd.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index b1edeb8642b8..30dc5f1978ab 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -19,7 +19,6 @@
 #include <linux/kernel.h>
 #include <linux/bitops.h>
 #include <linux/dma-mapping.h>
-#include <linux/virtio_config.h>
 #include <linux/cc_platform.h>
 
 #include <asm/tlbflush.h>
-- 
2.39.2

Re: [PATCH v2 0/2] x86/sev: Generalize sev_setup_arch()

[Alexander Shishkin]

Alexander Shishkin <alexander.shishkin@linux.intel.com> writes:

> Hi,
>
> Since previous version [0], I added 2/2, which is a minor cleanup.
>
> The main intention of this is to move sev_setup_arch() to mem_encrypt.c
> to reflect the fact that it's not SEV-specific, but covers TDX as well,
> although unintentionally.
>
> While looking at it, I also noticed that mem_encrypt_amd.c still
> includes virtio_config.h, which was needed for the code that since got
> moved to a different place (and even there doesn't require the include
> any more).

Gentle ping.

Regards,
--
Alex