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x86/io: Unroll string I/O when SEV is active

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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 <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: kvm@vger.kernel.org
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20171020143059.3291-14-brijesh.singh@amd.com
This commit is contained in:
Tom Lendacky
2017-10-20 09:30:55 -05:00
committed by Thomas Gleixner
parent 1958b5fc40
commit 606b21d4a6
2 changed files with 47 additions and 4 deletions
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43
arch/x86/include/asm/io.h
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@@ -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)