Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-23 Thread Adrian Hunter
On 23/10/24 01:30, Sean Christopherson wrote: > On Tue, Oct 22, 2024, Adrian Hunter wrote: >> On 22/10/24 19:30, Sean Christopherson wrote: > LOL, yeah, this needs to be burned with fire. It's wildly broken. So > for stable@, It doesn't seem wildly broken. Just the VMM passing

Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-22 Thread Andi Kleen
> > Out of curiosity, how much is Intel PT used purely for control flow tracing, > i.e. > without caring _at all_ about perceived execution time? It is very common, e.g. one major use of PT is control flow discovery in feedback fuzzers. -Andi

Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-22 Thread Sean Christopherson
On Tue, Oct 22, 2024, Adrian Hunter wrote: > On 22/10/24 19:30, Sean Christopherson wrote: > >>> LOL, yeah, this needs to be burned with fire. It's wildly broken. So > >>> for stable@, > >> > >> It doesn't seem wildly broken. Just the VMM passing invalid CPUID > >> and KVM not validating it. >

Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-22 Thread Adrian Hunter
On 22/10/24 19:30, Sean Christopherson wrote: > On Tue, Oct 22, 2024, Adrian Hunter wrote: >> On 14/10/24 21:25, Sean Christopherson wrote: Fixes: 2ef444f1600b ("KVM: x86: Add Intel PT context switch for each vcpu") Cc: sta...@vger.kernel.org >>> >>> This is way, way too big for stable@.

Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-22 Thread Sean Christopherson
On Tue, Oct 22, 2024, Adrian Hunter wrote: > On 14/10/24 21:25, Sean Christopherson wrote: > >> Fixes: 2ef444f1600b ("KVM: x86: Add Intel PT context switch for each vcpu") > >> Cc: sta...@vger.kernel.org > > > > This is way, way too big for stable@. Given that host/guest mode is > > disabled by

Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-22 Thread Adrian Hunter
On 14/10/24 21:25, Sean Christopherson wrote: > On Mon, Oct 14, 2024, Adrian Hunter wrote: >> Ensure Intel PT tracing is disabled before VM-Entry in Intel PT Host/Guest >> mode. >> >> Intel PT has 2 modes for tracing virtual machines. The default is System >> mode whereby host and guest output to t

Re: [PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-14 Thread Sean Christopherson
On Mon, Oct 14, 2024, Adrian Hunter wrote: > Ensure Intel PT tracing is disabled before VM-Entry in Intel PT Host/Guest > mode. > > Intel PT has 2 modes for tracing virtual machines. The default is System > mode whereby host and guest output to the host trace buffer. The other is > Host/Guest mode

[PATCH V13 03/14] KVM: x86: Fix Intel PT Host/Guest mode when host tracing also

2024-10-14 Thread Adrian Hunter
Ensure Intel PT tracing is disabled before VM-Entry in Intel PT Host/Guest mode. Intel PT has 2 modes for tracing virtual machines. The default is System mode whereby host and guest output to the host trace buffer. The other is Host/Guest mode whereby host and guest output to their own buffers. Ho