Commit-ID: 606b21d4a6498c23632a4693c81b7b24feedd038 Gitweb: https://git.kernel.org/tip/606b21d4a6498c23632a4693c81b7b24feedd038 Author: Tom Lendacky <[email protected]> AuthorDate: Fri, 20 Oct 2017 09:30:55 -0500 Committer: Thomas Gleixner <[email protected]> CommitDate: Tue, 7 Nov 2017 15:35:59 +0100
x86/io: Unroll string I/O when SEV is active Secure Encrypted Virtualization (SEV) does not support string I/O, so unroll the string I/O operation into a loop operating on one element at a time. [ tglx: Gave the static key a real name instead of the obscure __sev ] Signed-off-by: Tom Lendacky <[email protected]> Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Tested-by: Borislav Petkov <[email protected]> Cc: Andy Shevchenko <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: [email protected] Cc: David Laight <[email protected]> Cc: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/include/asm/io.h | 43 +++++++++++++++++++++++++++++++++++++++---- arch/x86/mm/mem_encrypt.c | 8 ++++++++ 2 files changed, 47 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 11398d5..93ae8ae 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -266,6 +266,21 @@ 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) \ { \ @@ -296,14 +311,34 @@ static inline unsigned type in##bwl##_p(int port) \ \ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ { \ - asm volatile("rep; outs" #bwl \ - : "+S"(addr), "+c"(count) : "d"(port) : "memory"); \ + if (sev_key_active()) { \ + unsigned type *value = (unsigned type *)addr; \ + while (count) { \ + out##bwl(*value, port); \ + value++; \ + count--; \ + } \ + } else { \ + asm volatile("rep; outs" #bwl \ + : "+S"(addr), "+c"(count) \ + : "d"(port) : "memory"); \ + } \ } \ \ static inline void ins##bwl(int port, void *addr, unsigned long count) \ { \ - asm volatile("rep; ins" #bwl \ - : "+D"(addr), "+c"(count) : "d"(port) : "memory"); \ + if (sev_key_active()) { \ + unsigned type *value = (unsigned type *)addr; \ + while (count) { \ + *value = in##bwl(port); \ + value++; \ + count--; \ + } \ + } else { \ + asm volatile("rep; ins" #bwl \ + : "+D"(addr), "+c"(count) \ + : "d"(port) : "memory"); \ + } \ } BUILDIO(b, b, char) diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index fd9c7bb..d29b783 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -41,6 +41,8 @@ static char sme_cmdline_off[] __initdata = "off"; */ u64 sme_me_mask __section(.data) = 0; EXPORT_SYMBOL_GPL(sme_me_mask); +DEFINE_STATIC_KEY_FALSE(sev_enable_key); +EXPORT_SYMBOL_GPL(sev_enable_key); static bool sev_enabled __section(.data); @@ -313,6 +315,12 @@ void __init mem_encrypt_init(void) if (sev_active()) dma_ops = &sev_dma_ops; + /* + * With SEV, we need to unroll the rep string I/O instructions. + */ + if (sev_active()) + static_branch_enable(&sev_enable_key); + pr_info("AMD %s active\n", sev_active() ? "Secure Encrypted Virtualization (SEV)" : "Secure Memory Encryption (SME)");
