From: Andrew Cooper Date: Fri, 6 Sep 2019 15:59:02 +0000 (+0100) Subject: x86/cpuid: Fix handling of the CPUID.7[0].eax levelling MSR X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=b50d78d0eaffb43d5f5ceeda55fa22c11f47d01b;p=people%2Fliuw%2Fxen.git x86/cpuid: Fix handling of the CPUID.7[0].eax levelling MSR 7a0 is an integer field, not a mask - taking the logical and of the hardware and policy values results in nonsense. Instead, take the policy value directly. Signed-off-by: Andrew Cooper Reviewed-by: Roger Pau Monné Reviewed-by: Jan Beulich --- diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c index 1e98fc8009..a744696c6b 100644 --- a/xen/arch/x86/domctl.c +++ b/xen/arch/x86/domctl.c @@ -218,11 +218,16 @@ static int update_domain_cpuid_info(struct domain *d, if ( is_pv_domain(d) && ((levelling_caps & LCAP_7ab0) == LCAP_7ab0) ) { uint64_t mask = cpuidmask_defaults._7ab0; - uint32_t eax = ctl->eax; - uint32_t ebx = p->feat._7b0; - if ( boot_cpu_data.x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON) ) - mask &= ((uint64_t)eax << 32) | ebx; + /* + * Leaf 7[0].eax is max_subleaf, not a feature mask. Take it + * wholesale from the policy, but clamp the features in 7[0].ebx + * per usual. + */ + if ( boot_cpu_data.x86_vendor & + (X86_VENDOR_AMD | X86_VENDOR_HYGON) ) + mask = (((uint64_t)p->feat.max_subleaf << 32) | + ((uint32_t)mask & p->feat._7b0)); d->arch.pv.cpuidmasks->_7ab0 = mask; }