Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
On Mon, Jan 8, 2018 at 12:07 PM, Liran Alon <LIRAN.ALON@xxxxxxxxxx> wrote:
>
>
> On 08/01/18 20:08, Paolo Bonzini wrote:
>>
>> Expose them to userspace, now that guests can use them.
>> I am not adding cpufeatures here to avoid having a kernel
>> that shows spec_ctrl in /proc/cpuinfo and actually has no
>> support whatsoever for IBRS/IBPB. Keep the ugly special-casing
>> for now, and clean it up once the generic arch/x86/ code
>> learns about them.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> ---
>> arch/x86/kvm/cpuid.c | 24 +++++++++++++++++++++---
>> arch/x86/kvm/x86.c | 1 +
>> 2 files changed, 22 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index 767af697c20c..5f43a5940275 100644
>> --- a/arch/x86/kvm/cpuid.c
>> +++ b/arch/x86/kvm/cpuid.c
>> @@ -397,7 +397,12 @@ static inline int __do_cpuid_ent(struct
>> kvm_cpuid_entry2 *entry, u32 function,
>>
>> /* cpuid 7.0.edx*/
>> const u32 kvm_cpuid_7_0_edx_x86_features =
>> - KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS);
>> + KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS) |
>> + KF(SPEC_CTRL) | KF(STIBP);
>> +
>> + /* cpuid 0x80000008.edx */
>> + const u32 kvm_cpuid_80000008_ebx_x86_features =
>> + KF(IBPB_SUPPORT);
>>
>> /* all calls to cpuid_count() should be made on the same cpu */
>> get_cpu();
>> @@ -483,7 +488,14 @@ static inline int __do_cpuid_ent(struct
>> kvm_cpuid_entry2 *entry, u32 function,
>> if (!tdp_enabled ||
>> !boot_cpu_has(X86_FEATURE_OSPKE))
>> entry->ecx &= ~F(PKU);
>> entry->edx &= kvm_cpuid_7_0_edx_x86_features;
>> - entry->edx &= get_scattered_cpuid_leaf(7, 0,
>> CPUID_EDX);
>> + /*
>> + * FIXME: the special casing of SPEC_CTRL and
>> STIBP
>> + * can be removed once they become regular
>> + * cpufeatures.
>> + */
>> + entry->edx &= (
>> + get_scattered_cpuid_leaf(7, 0, CPUID_EDX)
>> |
>> + KF(SPEC_CTRL) | KF(STIBP));
>> } else {
>> entry->ebx = 0;
>> entry->ecx = 0;
>> @@ -651,7 +663,13 @@ static inline int __do_cpuid_ent(struct
>> kvm_cpuid_entry2 *entry, u32 function,
>> if (!g_phys_as)
>> g_phys_as = phys_as;
>> entry->eax = g_phys_as | (virt_as << 8);
>> - entry->ebx = entry->edx = 0;
>> + /*
>> + * FIXME: mask against cpufeatures, with
>> + * get_scattered_cpuid_leaf(0x80000008, 0, CPUID_EBX),
>> + * once IBPB_SUPPORT becomes a regular cpufeature.
>> + */
>> + entry->ebx &= kvm_cpuid_80000008_ebx_x86_features;
>> + entry->edx = 0;
>> break;
>> }
>> case 0x80000019:
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index daa1918031df..4abb37d9f4d8 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -1032,6 +1032,7 @@ unsigned int kvm_get_pt_addr_cnt(void)
>> MSR_IA32_RTIT_ADDR1_A, MSR_IA32_RTIT_ADDR1_B,
>> MSR_IA32_RTIT_ADDR2_A, MSR_IA32_RTIT_ADDR2_B,
>> MSR_IA32_RTIT_ADDR3_A, MSR_IA32_RTIT_ADDR3_B,
>> + MSR_IA32_SPEC_CTRL,
>> };
>>
>> static unsigned num_msrs_to_save;
>>
>
> Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx>
