On Thu, 2020-05-21 at 10:40 +0200, Paolo Bonzini wrote:
> On 21/05/20 08:44, Tao Xu wrote:
> > I am sorry, I mean:
> > By default, we don't expose WAITPKG to guest. For QEMU, we can use
> > "-overcommit cpu-pm=on" to use WAITPKG.
>
> But UMONITOR, UMWAIT and TPAUSE are not NOPs on older processors
On Tue, 2020-05-26 at 18:21 -0700, Sean Christopherson wrote:
> On Sat, May 23, 2020 at 07:14:55PM +0300, Maxim Levitsky wrote:
> > This msr is only available when the host supports WAITPKG feature.
> >
> > This breaks a nested guest, if the L1 hypervisor is set to ignore
> > unknown msrs, because
On Sat, May 23, 2020 at 07:14:55PM +0300, Maxim Levitsky wrote:
> This msr is only available when the host supports WAITPKG feature.
>
> This breaks a nested guest, if the L1 hypervisor is set to ignore
> unknown msrs, because the only other safety check that the
> kernel does is that it attempts
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to ignore
unknown msrs, because the only other safety check that the
kernel does is that it attempts to read the msr and
rejects it if it gets an exception.
Fixes: 6e3ba4abce
On 21/05/20 08:44, Tao Xu wrote:
>
> I am sorry, I mean:
> By default, we don't expose WAITPKG to guest. For QEMU, we can use
> "-overcommit cpu-pm=on" to use WAITPKG.
But UMONITOR, UMWAIT and TPAUSE are not NOPs on older processors (which
I should have checked before committing your patch, I adm
On 21/05/20 06:33, Xiaoyao Li wrote:
> I remember there is certainly some reason why we don't expose WAITPKG to
> guest by default.
That's a userspace policy decision. KVM_GET_SUPPORTED_CPUID should
still tell userspace that it's supported.
Paolo
> Tao, please help clarify it.
On 5/21/2020 12:56 AM, Maxim Levitsky wrote:
On Wed, 2020-05-20 at 18:33 +0200, Vitaly Kuznetsov wrote:
Maxim Levitsky writes:
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to ignore
unknown msrs, because the only o
On 5/21/2020 2:37 PM, Xiaoyao Li wrote:
On 5/21/2020 1:28 PM, Tao Xu wrote:
On 5/21/2020 12:33 PM, Xiaoyao Li wrote:
On 5/21/2020 5:05 AM, Paolo Bonzini wrote:
On 20/05/20 18:07, Maxim Levitsky wrote:
This msr is only available when the host supports WAITPKG feature.
This breaks a neste
On 5/21/2020 1:28 PM, Tao Xu wrote:
On 5/21/2020 12:33 PM, Xiaoyao Li wrote:
On 5/21/2020 5:05 AM, Paolo Bonzini wrote:
On 20/05/20 18:07, Maxim Levitsky wrote:
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to igno
On 5/21/2020 12:33 PM, Xiaoyao Li wrote:
On 5/21/2020 5:05 AM, Paolo Bonzini wrote:
On 20/05/20 18:07, Maxim Levitsky wrote:
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to ignore
unknown msrs, because the only ot
On 5/21/2020 5:05 AM, Paolo Bonzini wrote:
On 20/05/20 18:07, Maxim Levitsky wrote:
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to ignore
unknown msrs, because the only other safety check that the
kernel does is that
On Wed, 2020-05-20 at 23:05 +0200, Paolo Bonzini wrote:
> On 20/05/20 18:07, Maxim Levitsky wrote:
> > This msr is only available when the host supports WAITPKG feature.
> >
> > This breaks a nested guest, if the L1 hypervisor is set to ignore
> > unknown msrs, because the only other safety check
On 20/05/20 18:07, Maxim Levitsky wrote:
> This msr is only available when the host supports WAITPKG feature.
>
> This breaks a nested guest, if the L1 hypervisor is set to ignore
> unknown msrs, because the only other safety check that the
> kernel does is that it attempts to read the msr and
> r
On Wed, 2020-05-20 at 19:15 +0200, Vitaly Kuznetsov wrote:
> Maxim Levitsky writes:
>
> > On Wed, 2020-05-20 at 18:33 +0200, Vitaly Kuznetsov wrote:
> > > Maxim Levitsky writes:
> > >
> > > > This msr is only available when the host supports WAITPKG feature.
> > > >
> > > > This breaks a neste
Maxim Levitsky writes:
> On Wed, 2020-05-20 at 18:33 +0200, Vitaly Kuznetsov wrote:
>> Maxim Levitsky writes:
>>
>> > This msr is only available when the host supports WAITPKG feature.
>> >
>> > This breaks a nested guest, if the L1 hypervisor is set to ignore
>> > unknown msrs, because the on
On Wed, 2020-05-20 at 18:33 +0200, Vitaly Kuznetsov wrote:
> Maxim Levitsky writes:
>
> > This msr is only available when the host supports WAITPKG feature.
> >
> > This breaks a nested guest, if the L1 hypervisor is set to ignore
> > unknown msrs, because the only other safety check that the
>
Maxim Levitsky writes:
> This msr is only available when the host supports WAITPKG feature.
>
> This breaks a nested guest, if the L1 hypervisor is set to ignore
> unknown msrs, because the only other safety check that the
> kernel does is that it attempts to read the msr and
> rejects it if it g
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to ignore
unknown msrs, because the only other safety check that the
kernel does is that it attempts to read the msr and
rejects it if it gets an exception.
Fixes: 6e3ba4abce
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