On 1/24/22 09:02, Like Xu wrote:
case 0xd: {
- u64 guest_perm = xstate_get_guest_group_perm();
+ u64 supported_xcr0 = supported_xcr0 & xstate_get_guest_group_perm();
- entry->eax &= supported_xcr0 & guest_perm;
+ entry->eax &= supported_xcr0;
entry->ebx = xstate_required_size(supported_xcr0, false);
entry->ecx = entry->ebx;
- entry->edx &= (supported_xcr0 & guest_perm) >> 32;
+ entry->edx &= supported_xcr0 >> 32;
if (!supported_xcr0)
break;
No, please don't use this kind of shadowing. I'm not even sure it
works, and one would have to read the C standard or look at the
disassembly to be sure. Perhaps this instead could be an idea:
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 3dcd58a138a9..03deb51d8d18 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 supported_xcr0 = supported_xcr0 & xstate_get_guest_group_perm();
+ u64 permitted_xcr0 = supported_xcr0 & xstate_get_guest_group_perm();
- entry->eax &= supported_xcr0;
- entry->ebx = xstate_required_size(supported_xcr0, false);
+#define supported_xcr0 DO_NOT_USE_ME
+ entry->eax &= permitted_xcr0;
+ entry->ebx = xstate_required_size(permitted_xcr0, false);
entry->ecx = entry->ebx;
- entry->edx &= supported_xcr0 >> 32;
- if (!supported_xcr0)
+ entry->edx &= permitted_xcr0 >> 32;
+ if (!permitted_xcr0)
break;
entry = do_host_cpuid(array, function, 1);
@@ -902,7 +903,7 @@ 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 | supported_xss,
true);
else {
WARN_ON_ONCE(supported_xss != 0);
@@ -913,7 +914,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
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))
s_state = true;
@@ -942,6 +943,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->edx = 0;
}
break;
+#undef supported_xcr0
}
case 0x12:
/* Intel SGX */
or alternatively add
u64 permitted_xss = supported_xss;
so that you use "permitted" consistently. Anybody can vote on what they
prefer (including "permitted_xcr0" and no #define/#undef).
Paolo
