| Message ID | 20200201185218.24473-7-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Introduce KVM cpu caps | expand |
Sean Christopherson <sean.j.christopherson@intel.com> writes: > 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. > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > arch/x86/kvm/cpuid.c | 37 ++++++++++++++++++++++--------------- > 1 file changed, 22 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index e5cf1e0cf84a..fc8540596386 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -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; Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index e5cf1e0cf84a..fc8540596386 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -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;
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. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/cpuid.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-)