On Fri, 2023-03-10 at 13:42 -0800, Sean Christopherson wrote: > Check "this" CPU instead of the boot CPU when querying SVM support so that > the per-CPU checks done during hardware enabling actually function as > intended, i.e. will detect issues where SVM isn't support on all CPUs. > > Disable migration for the use from svm_init() mostly so that the standard > accessors for the per-CPU data can be used without getting yelled at by > CONFIG_DEBUG_PREEMPT=y sanity checks. Preventing the "disabled by BIOS" > error message from reporting the wrong CPU is largely a bonus, as ensuring > a stable CPU during module load is a non-goal for KVM. > > Link: https://lore.kernel.org/all/ZAdxNgv0M6P63odE@xxxxxxxxxx > Cc: Kai Huang <kai.huang@xxxxxxxxx> > Cc: Chao Gao <chao.gao@xxxxxxxxx> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Should we add: Fixes: c82a5c5c53c5 ("KVM: x86: Do compatibility checks when onlining CPU") As that commit introduced using raw_smp_processor_id() to get CPU id in kvm_is_svm_supported() and print the CPU id out in error message? > --- > arch/x86/kvm/svm/svm.c | 25 +++++++++++++++++++------ > 1 file changed, 19 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 2934f185960d..f04b61c3d9d8 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -520,18 +520,20 @@ static void svm_init_osvw(struct kvm_vcpu *vcpu) > vcpu->arch.osvw.status |= 1; > } > > -static bool kvm_is_svm_supported(void) > +static bool __kvm_is_svm_supported(void) > { > - int cpu = raw_smp_processor_id(); > + int cpu = smp_processor_id(); Since we have made sure __kvm_is_svm_supported() is always performed on a stable cpu, should we keep using raw_smp_processor_id()? It is faster than smp_processor_id() when CONFIG_DEBUG_PREEMPT=y, but yes the latter can help to catch bug. > + struct cpuinfo_x86 *c = &cpu_data(cpu); > + > u64 vm_cr; > > - if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && > - boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) { > + if (c->x86_vendor != X86_VENDOR_AMD && > + c->x86_vendor != X86_VENDOR_HYGON) { > pr_err("CPU %d isn't AMD or Hygon\n", cpu); > return false; > } > > - if (!boot_cpu_has(X86_FEATURE_SVM)) { > + if (!cpu_has(c, X86_FEATURE_SVM)) { > pr_err("SVM not supported by CPU %d\n", cpu); > return false; > } > @@ -550,9 +552,20 @@ static bool kvm_is_svm_supported(void) > return true; > } > > +static bool kvm_is_svm_supported(void) > +{ > + bool supported; > + > + migrate_disable(); > + supported = __kvm_is_svm_supported(); > + migrate_enable(); > + > + return supported; > +} > + > static int svm_check_processor_compat(void) > { > - if (!kvm_is_svm_supported()) > + if (!__kvm_is_svm_supported()) > return -EIO; > > return 0; > -- > 2.40.0.rc1.284.g88254d51c5-goog >
