Commit 1ffce092 authored by Like Xu's avatar Like Xu Committed by Paolo Bonzini
Browse files

KVM: x86/cpuid: Exclude unpermitted xfeatures sizes at KVM_GET_SUPPORTED_CPUID 



With the help of xstate_get_guest_group_perm(), KVM can exclude unpermitted
xfeatures in cpuid.0xd.0.eax, in which case the corresponding xfeatures
sizes should also be matched to the permitted xfeatures.

To fix this inconsistency, the permitted_xcr0 and permitted_xss are defined
consistently, which implies 'supported' plus certain permissions for this
task, and it also fixes cpuid.0xd.1.ebx and later leaf-by-leaf queries.

Fixes: 445ecdf7 ("kvm: x86: Exclude unpermitted xfeatures at KVM_GET_SUPPORTED_CPUID")
Signed-off-by: default avatarLike Xu <likexu@tencent.com>
Message-Id: <20220125115223.33707-1-likexu@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 35fe7cfb

arch/x86/kvm/cpuid.c

+13 −12
Original line number Diff line number Diff line
@@ -899,13 +899,14 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
		}

		break;

	case 0xd: {

		u64 guest_perm = xstate_get_guest_group_perm();

		u64 permitted_xcr0 = supported_xcr0 & xstate_get_guest_group_perm();

		u64 permitted_xss = supported_xss;



		entry->eax &= supported_xcr0 & guest_perm;

		entry->ebx = xstate_required_size(supported_xcr0, false);

		entry->eax &= permitted_xcr0;

		entry->ebx = xstate_required_size(permitted_xcr0, false);

		entry->ecx = entry->ebx;

		entry->edx &= (supported_xcr0 & guest_perm) >> 32;

		if (!supported_xcr0)

		entry->edx &= permitted_xcr0 >> 32;

		if (!permitted_xcr0)

			break;



		entry = do_host_cpuid(array, function, 1);
@@ -914,20 +915,20 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 


		cpuid_entry_override(entry, CPUID_D_1_EAX);

		if (entry->eax & (F(XSAVES)|F(XSAVEC)))

			entry->ebx = xstate_required_size(supported_xcr0 | supported_xss,

			entry->ebx = xstate_required_size(permitted_xcr0 | permitted_xss,

							  true);

		else {

			WARN_ON_ONCE(supported_xss != 0);

			WARN_ON_ONCE(permitted_xss != 0);

			entry->ebx = 0;

		}

		entry->ecx &= supported_xss;

		entry->edx &= supported_xss >> 32;

		entry->ecx &= permitted_xss;

		entry->edx &= permitted_xss >> 32;



		for (i = 2; i < 64; ++i) {

			bool s_state;

			if (supported_xcr0 & BIT_ULL(i))

			if (permitted_xcr0 & BIT_ULL(i))

				s_state = false;

			else if (supported_xss & BIT_ULL(i))

			else if (permitted_xss & BIT_ULL(i))

				s_state = true;

			else

				continue;
@@ -941,7 +942,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
			 * invalid sub-leafs.  Only valid sub-leafs should

			 * reach this point, and they should have a non-zero

			 * save state size.  Furthermore, check whether the

			 * processor agrees with supported_xcr0/supported_xss

			 * processor agrees with permitted_xcr0/permitted_xss

			 * on whether this is an XCR0- or IA32_XSS-managed area.

			 */

			if (WARN_ON_ONCE(!entry->eax || (entry->ecx & 0x1) != s_state)) {