The following commit has been merged into the x86/sev branch of tip: Commit-ID: 8260b9820f7050461b8969305bbd8cb5654f0c74 Gitweb: https://git.kernel.org/tip/8260b9820f7050461b8969305bbd8cb5654f0c74 Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> AuthorDate: Mon, 06 Dec 2021 16:55:03 +03:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Wed, 08 Dec 2021 16:49:42 +01:00 x86/sev: Use CC_ATTR attribute to generalize string I/O unroll INS/OUTS are not supported in TDX guests and cause #UD. Kernel has to avoid them when running in TDX guest. To support existing usage, string I/O operations are unrolled using IN/OUT instructions. AMD SEV platform implements this support by adding unroll logic in ins#bwl()/outs#bwl() macros with SEV-specific checks. Since TDX VM guests will also need similar support, use CC_ATTR_GUEST_UNROLL_STRING_IO and generic cc_platform_has() API to implement it. String I/O helpers were the last users of sev_key_active() interface and sev_enable_key static key. Remove them. [ bp: Move comment too and do not delete it. ] Suggested-by: Tom Lendacky <thomas.lendacky@xxxxxxx> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx> Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx> Tested-by: Tom Lendacky <thomas.lendacky@xxxxxxx> Link: https://lkml.kernel.org/r/20211206135505.75045-2-kirill.shutemov@xxxxxxxxxxxxxxx --- arch/x86/include/asm/io.h | 20 +++----------------- arch/x86/kernel/cc_platform.c | 8 ++++++++ arch/x86/mm/mem_encrypt.c | 10 ---------- include/linux/cc_platform.h | 11 +++++++++++ 4 files changed, 22 insertions(+), 27 deletions(-) diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 5c6a4af..f6d91ec 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -40,6 +40,7 @@ #include <linux/string.h> #include <linux/compiler.h> +#include <linux/cc_platform.h> #include <asm/page.h> #include <asm/early_ioremap.h> #include <asm/pgtable_types.h> @@ -256,21 +257,6 @@ static inline void slow_down_io(void) #endif -#ifdef CONFIG_AMD_MEM_ENCRYPT -#include <linux/jump_label.h> - -extern struct static_key_false sev_enable_key; -static inline bool sev_key_active(void) -{ - return static_branch_unlikely(&sev_enable_key); -} - -#else /* !CONFIG_AMD_MEM_ENCRYPT */ - -static inline bool sev_key_active(void) { return false; } - -#endif /* CONFIG_AMD_MEM_ENCRYPT */ - #define BUILDIO(bwl, bw, type) \ static inline void out##bwl(unsigned type value, int port) \ { \ @@ -301,7 +287,7 @@ static inline unsigned type in##bwl##_p(int port) \ \ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ { \ - if (sev_key_active()) { \ + if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) { \ unsigned type *value = (unsigned type *)addr; \ while (count) { \ out##bwl(*value, port); \ @@ -317,7 +303,7 @@ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ \ static inline void ins##bwl(int port, void *addr, unsigned long count) \ { \ - if (sev_key_active()) { \ + if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) { \ unsigned type *value = (unsigned type *)addr; \ while (count) { \ *value = in##bwl(port); \ diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c index 03bb2f3..8a25b1c 100644 --- a/arch/x86/kernel/cc_platform.c +++ b/arch/x86/kernel/cc_platform.c @@ -50,6 +50,14 @@ static bool amd_cc_platform_has(enum cc_attr attr) case CC_ATTR_GUEST_STATE_ENCRYPT: return sev_status & MSR_AMD64_SEV_ES_ENABLED; + /* + * With SEV, the rep string I/O instructions need to be unrolled + * but SEV-ES supports them through the #VC handler. + */ + case CC_ATTR_GUEST_UNROLL_STRING_IO: + return (sev_status & MSR_AMD64_SEV_ENABLED) && + !(sev_status & MSR_AMD64_SEV_ES_ENABLED); + default: return false; } diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index 3548730..b520021 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -43,8 +43,6 @@ u64 sme_me_mask __section(".data") = 0; u64 sev_status __section(".data") = 0; u64 sev_check_data __section(".data") = 0; EXPORT_SYMBOL(sme_me_mask); -DEFINE_STATIC_KEY_FALSE(sev_enable_key); -EXPORT_SYMBOL_GPL(sev_enable_key); /* Buffer used for early in-place encryption by BSP, no locking needed */ static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE); @@ -499,14 +497,6 @@ void __init mem_encrypt_init(void) /* Call into SWIOTLB to update the SWIOTLB DMA buffers */ swiotlb_update_mem_attributes(); - /* - * With SEV, we need to unroll the rep string I/O instructions, - * but SEV-ES supports them through the #VC handler. - */ - if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && - !cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) - static_branch_enable(&sev_enable_key); - print_mem_encrypt_feature_info(); } diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h index a075b70..efd8205 100644 --- a/include/linux/cc_platform.h +++ b/include/linux/cc_platform.h @@ -61,6 +61,17 @@ enum cc_attr { * Examples include SEV-ES. */ CC_ATTR_GUEST_STATE_ENCRYPT, + + /** + * @CC_ATTR_GUEST_UNROLL_STRING_IO: String I/O is implemented with + * IN/OUT instructions + * + * The platform/OS is running as a guest/virtual machine and uses + * IN/OUT instructions in place of string I/O. + * + * Examples include TDX guest & SEV. + */ + CC_ATTR_GUEST_UNROLL_STRING_IO, }; #ifdef CONFIG_ARCH_HAS_CC_PLATFORM
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