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KVM: x86: Move CPUID 0xD.1 handling out of the index>0 loop

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Mov the sub-leaf 1 handling for CPUID 0xD out of the index>0 loop so
that the loop only handles index>2.  Sub-leafs 2+ have identical
semantics, whereas sub-leaf 1 is effectively a feature sub-leaf.

Moving sub-leaf 1 out of the loop does duplicate a bit of code, but
the nent/maxnent code will be consolidated in a future patch, and
duplicating the clear of ECX/EDX is arguably a good thing as the reasons
for clearing said registers are completely different.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2020-03-02 15:56:09 -08:00 committed by Paolo Bonzini
parent 0fc6267187
commit 3dc4a9cf05
1 changed files with 22 additions and 15 deletions
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37
arch/x86/kvm/cpuid.c
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@ -653,26 +653,33 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
if (!supported)
break;
for (idx = 1, i = 1; idx < 64; ++idx) {
if (*nent >= maxnent)
goto out;
do_host_cpuid(&entry[1], function, 1);
++*nent;
entry[1].eax &= kvm_cpuid_D_1_eax_x86_features;
cpuid_mask(&entry[1].eax, CPUID_D_1_EAX);
if (entry[1].eax & (F(XSAVES)|F(XSAVEC)))
entry[1].ebx = xstate_required_size(supported, true);
else
entry[1].ebx = 0;
/* Saving XSS controlled state via XSAVES isn't supported. */
entry[1].ecx = 0;
entry[1].edx = 0;
for (idx = 2, i = 2; idx < 64; ++idx) {
u64 mask = ((u64)1 << idx);
if (*nent >= maxnent)
goto out;
do_host_cpuid(&entry[i], function, idx);
if (idx == 1) {
entry[i].eax &= kvm_cpuid_D_1_eax_x86_features;
cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
entry[i].ebx = 0;
if (entry[i].eax & (F(XSAVES)|F(XSAVEC)))
entry[i].ebx =
xstate_required_size(supported,
true);
} else {
if (entry[i].eax == 0 || !(supported & mask))
continue;
if (WARN_ON_ONCE(entry[i].ecx & 1))
continue;
}
if (entry[i].eax == 0 || !(supported & mask))
continue;
if (WARN_ON_ONCE(entry[i].ecx & 1))
continue;
entry[i].ecx = 0;
entry[i].edx = 0;
++*nent;