KVM: x86: Move CPUID 0xD.1 handling out of the index>0 loop (3dc4a9cf) · Commits · 戴 / test

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>

arch/x86/kvm/cpuid.c

+22 −15

Original line number	Diff line number	Diff line
		@@ -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;
		}
		entry[i].ecx = 0;
		entry[i].edx = 0;
		++*nent;

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