On 02.03.20 20:57, Sean Christopherson wrote:
Rework kvm_cpuid() to query entry->function when adjusting the output values so that the original function (in the aptly named "function") is preserved for tracing. This fixes a bug where trace_kvm_cpuid() will trace the max function for a range instead of the requested function if the requested function is out-of-range and an entry for the max function exists. Fixes: 43561123ab37 ("kvm: x86: Improve emulation of CPUID leaves 0BH and 1FH") Reported-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> Cc: Jim Mattson <jmattson@xxxxxxxxxx> Cc: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> --- arch/x86/kvm/cpuid.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index b1c469446b07..6be012937eba 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -997,12 +997,12 @@ static bool cpuid_function_in_range(struct kvm_vcpu *vcpu, u32 function) return max && function <= max->eax; }+/* Returns true if the requested leaf/function exists in guest CPUID. */bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, bool check_limit) { - u32 function = *eax, index = *ecx; + const u32 function = *eax, index = *ecx; struct kvm_cpuid_entry2 *entry; - struct kvm_cpuid_entry2 *max; bool found;entry = kvm_find_cpuid_entry(vcpu, function, index);@@ -1015,18 +1015,17 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, */ if (!entry && check_limit && !guest_cpuid_is_amd(vcpu) && !cpuid_function_in_range(vcpu, function)) { - max = kvm_find_cpuid_entry(vcpu, 0, 0); - if (max) { - function = max->eax; - entry = kvm_find_cpuid_entry(vcpu, function, index); - } + entry = kvm_find_cpuid_entry(vcpu, 0, 0); + if (entry) + entry = kvm_find_cpuid_entry(vcpu, entry->eax, index); } if (entry) { *eax = entry->eax; *ebx = entry->ebx; *ecx = entry->ecx; *edx = entry->edx; - if (function == 7 && index == 0) { + + if (entry->function == 7 && index == 0) { u64 data; if (!__kvm_get_msr(vcpu, MSR_IA32_TSX_CTRL, &data, true) && (data & TSX_CTRL_CPUID_CLEAR))
What about the !entry case below this? It was impacted by the function capping so far, not it's no longer.
Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux
