From: Jan Beulich Date: Thu, 9 Apr 2020 07:30:14 +0000 (+0200) Subject: x86/vPMU: don't blindly assume IA32_PERF_CAPABILITIES MSR exists X-Git-Tag: RELEASE-4.12.3~42 X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=3c37292c844a23beffc802192600386e2ea6888c;p=xen.git x86/vPMU: don't blindly assume IA32_PERF_CAPABILITIES MSR exists Just like VMX'es lbr_tsx_fixup_check() the respective CPUID bit should be consulted first. Reported-by: Farrah Chen Signed-off-by: Jan Beulich Acked-by: Andrew Cooper master commit: 15c39c7c913f26fba40231e103ce1ffa6101e7c9 master date: 2020-02-26 17:35:48 +0100 --- diff --git a/xen/arch/x86/cpu/vpmu_intel.c b/xen/arch/x86/cpu/vpmu_intel.c index 6e27f6ec8e..75aa11c6ad 100644 --- a/xen/arch/x86/cpu/vpmu_intel.c +++ b/xen/arch/x86/cpu/vpmu_intel.c @@ -900,7 +900,6 @@ int vmx_vpmu_initialise(struct vcpu *v) int __init core2_vpmu_init(void) { - u64 caps; unsigned int version = 0; unsigned int i; @@ -932,8 +931,14 @@ int __init core2_vpmu_init(void) arch_pmc_cnt = core2_get_arch_pmc_count(); fixed_pmc_cnt = core2_get_fixed_pmc_count(); - rdmsrl(MSR_IA32_PERF_CAPABILITIES, caps); - full_width_write = (caps >> 13) & 1; + + if ( cpu_has_pdcm ) + { + uint64_t caps; + + rdmsrl(MSR_IA32_PERF_CAPABILITIES, caps); + full_width_write = (caps >> 13) & 1; + } fixed_ctrl_mask = ~((1ull << (fixed_pmc_cnt * FIXED_CTR_CTRL_BITS)) - 1); /* mask .AnyThread bits for all fixed counters */