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author | Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> | 2021-12-06 16:55:03 +0300 |
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committer | Borislav Petkov <bp@suse.de> | 2021-12-08 16:49:42 +0100 |
commit | 8260b9820f7050461b8969305bbd8cb5654f0c74 (patch) | |
tree | 81ab83711298a1e04d4b819ce783a7393b31541c /arch/x86/kernel/cc_platform.c | |
parent | 75cc9a84c9eb36e436e3fcee5158fe31d1dfd78f (diff) | |
download | linux-8260b9820f7050461b8969305bbd8cb5654f0c74.tar.gz linux-8260b9820f7050461b8969305bbd8cb5654f0c74.tar.bz2 linux-8260b9820f7050461b8969305bbd8cb5654f0c74.zip |
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@amd.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20211206135505.75045-2-kirill.shutemov@linux.intel.com
Diffstat (limited to 'arch/x86/kernel/cc_platform.c')
-rw-r--r-- | arch/x86/kernel/cc_platform.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c index 03bb2f343ddb..8a25b1c0d480 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; } |