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: 445ecdf79be0 ("kvm: x86: Exclude unpermitted xfeatures at KVM_GET_SUPPORTED_CPUID")
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220125115223.33707-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 89d7822..8e2704b 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -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)) {