Commit cc04b6a2 authored by Jing Liu's avatar Jing Liu Committed by Paolo Bonzini
Browse files

kvm: x86: Fix xstate_required_size() to follow XSTATE alignment rule 



CPUID.0xD.1.EBX enumerates the size of the XSAVE area (in compacted
format) required by XSAVES. If CPUID.0xD.i.ECX[1] is set for a state
component (i), this state component should be located on the next
64-bytes boundary following the preceding state component in the
compacted layout.

Fix xstate_required_size() to follow the alignment rule. AMX is the
first state component with 64-bytes alignment to catch this bug.

Signed-off-by: default avatarJing Liu <jing2.liu@intel.com>
Signed-off-by: default avatarYang Zhong <yang.zhong@intel.com>
Message-Id: <20220105123532.12586-4-yang.zhong@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 36487e62

arch/x86/kvm/cpuid.c

+5 −1
Original line number Diff line number Diff line
@@ -42,7 +42,11 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) 
		if (xstate_bv & 0x1) {

		        u32 eax, ebx, ecx, edx, offset;

		        cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx);

			offset = compacted ? ret : ebx;

			/* ECX[1]: 64B alignment in compacted form */

			if (compacted)

				offset = (ecx & 0x2) ? ALIGN(ret, 64) : ret;

			else

				offset = ebx;

			ret = max(ret, offset + eax);

		}