| Message ID | 20200129234640.8147-26-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Purge kvm_x86_ops->*_supported() | expand |
On Wed, Jan 29, 2020 at 03:46:39PM -0800, Sean Christopherson wrote: > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index d06fb54c9c0d..ca766c460318 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -409,7 +409,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, > unsigned f_gbpages = 0; > unsigned f_lm = 0; > #endif > - unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0; > > /* cpuid 1.edx */ > const u32 kvm_cpuid_1_edx_x86_features = > @@ -648,22 +647,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, > break; > } > /* Intel PT */ > - case 0x14: { > - int t, times = entry->eax; > - > - if (!f_intel_pt) { > - entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > - break; > - } > - > - for (t = 1; t <= times; ++t) { > - if (*nent >= maxnent) > - goto out; > - do_host_cpuid(&entry[t], function, t); > - ++*nent; > - } > + case 0x14: > break; > - } > case KVM_CPUID_SIGNATURE: { > static const char signature[12] = "KVMKVMKVM\0\0"; > const u32 *sigptr = (const u32 *)signature; > @@ -778,6 +763,21 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, > > kvm_x86_ops->set_supported_cpuid(entry); > > + /* > + * Add feature-dependent sub-leafs after ->set_supported_cpuid() to > + * properly handle the feature being disabled by SVM/VMX. > + */ > + if (function == 0x14) { > + int t, times = entry->eax; > + > + for (t = 1; t <= times; ++t) { > + if (*nent >= maxnent) > + goto out; > + do_host_cpuid(&entry[t], function, t); > + ++*nent; > + } > + } > + > r = 0; I belatedly thought of an alternative that I think I like better. Instead of adding the sub-leafs in common code, introduce a new kvm_x86_ops hook to add vendor specific sub-leafs, e.g.: kvm_x86_ops->set_supported_cpuid(entry); r = kvm_x86_ops->add_cpuid_sub_leafs(entry, nent, maxent, do_host_cpuid); That gets Intel PT (and SGX if/when it gets merged) sub-leafs out of the common x86 code without polluting ->set_supported_cpuid with the extra params and return value. The other hiccup is that SGX will want access to cpuid_mask(), but I don't see an issue with moving that to cpuid.h.
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index d06fb54c9c0d..ca766c460318 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -409,7 +409,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, unsigned f_gbpages = 0; unsigned f_lm = 0; #endif - unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0; /* cpuid 1.edx */ const u32 kvm_cpuid_1_edx_x86_features = @@ -648,22 +647,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, break; } /* Intel PT */ - case 0x14: { - int t, times = entry->eax; - - if (!f_intel_pt) { - entry->eax = entry->ebx = entry->ecx = entry->edx = 0; - break; - } - - for (t = 1; t <= times; ++t) { - if (*nent >= maxnent) - goto out; - do_host_cpuid(&entry[t], function, t); - ++*nent; - } + case 0x14: break; - } case KVM_CPUID_SIGNATURE: { static const char signature[12] = "KVMKVMKVM\0\0"; const u32 *sigptr = (const u32 *)signature; @@ -778,6 +763,21 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, kvm_x86_ops->set_supported_cpuid(entry); + /* + * Add feature-dependent sub-leafs after ->set_supported_cpuid() to + * properly handle the feature being disabled by SVM/VMX. + */ + if (function == 0x14) { + int t, times = entry->eax; + + for (t = 1; t <= times; ++t) { + if (*nent >= maxnent) + goto out; + do_host_cpuid(&entry[t], function, t); + ++*nent; + } + } + r = 0; out: diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 350cdf91a576..a08ee7b2dddb 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -6068,6 +6068,9 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) cpuid_entry_clear(entry, X86_FEATURE_INVPCID); cpuid_entry_clear(entry, X86_FEATURE_INTEL_PT); break; + case 0x14: + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; + break; case 0x80000001: if (nested) cpuid_entry_set(entry, X86_FEATURE_SVM); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 35134dbed2f0..10c31aa40730 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7155,6 +7155,10 @@ static void vmx_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) if (vmx_umip_emulated()) cpuid_entry_set(entry, X86_FEATURE_UMIP); break; + case 0x14: + if (!vmx_pt_mode_is_host_guest()) + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; + break; case 0x80000001: if (!cpu_has_vmx_rdtscp()) cpuid_entry_clear(entry, X86_FEATURE_RDTSCP);
Move the clearing of the Intel PT CPUID leaf into vendor code to eliminate a call to ->pt_supported(). To handle clearing CPUID 0x14's index>0 sub-leafs, introduce the pattern of adding feature-dependent sub-leafs (index>0 sub-leafs whose existence is enumerated by index=0) after calling ->set_supported_cpuid(). The dependent sub-leafs pattern can be reused for future (Intel) features such as SGX to allow vendor code to disable the feature, e.g. via module param, without having to add a feature specific kvm_x86_ops hook. No functional change intended. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/cpuid.c | 32 ++++++++++++++++---------------- arch/x86/kvm/svm.c | 3 +++ arch/x86/kvm/vmx/vmx.c | 4 ++++ 3 files changed, 23 insertions(+), 16 deletions(-)