On 28.09.21 18:55, Paolo Bonzini wrote:
> On 21/09/21 01:51, Krish Sadhukhan wrote:
>> According to section "TLB Flush" in APM vol 2,
>>
>> "Support for TLB_CONTROL commands other than the first two, is
>> optional and is indicated by CPUID Fn8000_000A_EDX[FlushByAsid].
>>
>> All encodings of TLB_CONTROL not defined in the APM are reserved."
>>
>> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
>> ---
>> arch/x86/kvm/svm/nested.c | 19 +++++++++++++++++++
>> 1 file changed, 19 insertions(+)
>>
>> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
>> index 5e13357da21e..028cc2a1f028 100644
>> --- a/arch/x86/kvm/svm/nested.c
>> +++ b/arch/x86/kvm/svm/nested.c
>> @@ -235,6 +235,22 @@ static bool nested_svm_check_bitmap_pa(struct
>> kvm_vcpu *vcpu, u64 pa, u32 size)
>> kvm_vcpu_is_legal_gpa(vcpu, addr + size - 1);
>> }
>> +static bool nested_svm_check_tlb_ctl(struct kvm_vcpu *vcpu
, u8
>> tlb_ctl)
>> +{
>> + switch(tlb_ctl) {
>> + case TLB_CONTROL_DO_NOTHING:
>> + case TLB_CONTROL_FLUSH_ALL_ASID:
>> + return true;
>> + case TLB_CONTROL_FLUSH_ASID:
>> + case TLB_CONTROL_FLUSH_ASID_LOCAL:
>> + if (guest_cpuid_has(vcpu, X86_FEATURE_FLUSHBYASID))
>> + return true;
>> + fallthrough;
>
> Since nested FLUSHBYASID is not supported yet, this second set of case
> labels can go away.
>
> Queued with that change, thanks.
>
> Paolo
>
Are there any plans to support FLUSHBYASID in the future? It seems
VMWare Workstation and ESXi require this feature to run on top of KVM
[1]. This means that after the introduction of this check these VMs fail
to boot and report missing features. Hence, upgrading to a newer kernel
version is not an option for some users.
Sorry if I misunderstood something or if
this is not the right place to
ask.
[1]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2008583
