On 1/25/22 12:52, Like Xu wrote:
From: Like Xu <likexu@xxxxxxxxxxx>
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@xxxxxxxxxxx>
---
v1 -> v2 Changelog:
- Drop the use of shadow variable; (Paolo)
- Define permitted_xss consistently; (Kevin)
Previous:
https://lore.kernel.org/kvm/20220124080251.60558-1-likexu@xxxxxxxxxxx/
arch/x86/kvm/cpuid.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 3902c28fb6cb..07844d15dfdf 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -887,13 +887,14 @@ 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);
@@ -902,20 +903,20 @@ 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;
@@ -929,7 +930,7 @@ 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)) {
Queued, thanks.
Paolo
