From: Sean Christopherson <seanjc@google.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>, Jon Kohler <jon@nutanix.com>,
Babu Moger <babu.moger@amd.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
the arch/x86 maintainers <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Fenghua Yu <fenghua.yu@intel.com>,
Yu-cheng Yu <yu-cheng.yu@intel.com>,
Tony Luck <tony.luck@intel.com>, Uros Bizjak <ubizjak@gmail.com>,
Petteri Aimonen <jpa@git.mail.kapsi.fi>,
Kan Liang <kan.liang@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>,
Benjamin Thiel <b.thiel@posteo.de>,
Fan Yang <Fan_Yang@sjtu.edu.cn>, Juergen Gross <jgross@suse.com>,
Dave Jiang <dave.jiang@intel.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
kvm list <kvm@vger.kernel.org>
Subject: Re: [PATCH] KVM: x86: add hint to skip hidden rdpkru under kvm_load_host_xsave_state
Date: Mon, 17 May 2021 18:04:56 +0000 [thread overview]
Message-ID: <YKKwSLnkzc77HcnG@google.com> (raw)
In-Reply-To: <342a8ba9-037e-b841-f9b1-cb62e46c0db8@intel.com>
On Mon, May 17, 2021, Dave Hansen wrote:
> On 5/17/21 10:49 AM, Andy Lutomirski wrote:
> >> The least awful solution would be to have the NMI handler restore
> >> the host's PKRU. The NMI handler would need to save/restore the
> >> register, a la CR2, but the whole thing could be optimized to run
> >> if and only if the NMI lands in the window where the guest's PKRU
> >> is loaded.
> >
> > Or set a flag causing nmi_uaccess_ok() to return false.
>
> Oh, that doesn't sound too bad. The VMENTER/EXIT paths are also
> essentially a context switch.
I like that idea, too.
The flag might also be useful to fix the issue where the NMI handler activates
PEBS after KVM disables it. Jim?
> Will widening the window where nmi_uaccess_okay()==false anger any of
> the perf folks? It looks like perf knows how to handle it nicely.
next prev parent reply other threads:[~2021-05-17 18:05 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-07 16:44 [PATCH] KVM: x86: add hint to skip hidden rdpkru under kvm_load_host_xsave_state Jon Kohler
2021-05-07 16:52 ` Paolo Bonzini
2021-05-07 16:58 ` Dave Hansen
2021-05-07 17:13 ` Jon Kohler
2021-05-14 5:11 ` Andy Lutomirski
2021-05-17 2:50 ` Jon Kohler
2021-05-17 16:35 ` Tom Lendacky
2021-05-17 7:46 ` Paolo Bonzini
2021-05-17 17:39 ` Sean Christopherson
2021-05-17 17:55 ` Dave Hansen
2021-05-17 18:02 ` Sean Christopherson
[not found] ` <4e6f7056-6b66-46b9-9eac-922ae1c7b526@www.fastmail.com>
2021-05-17 17:59 ` Dave Hansen
2021-05-17 18:04 ` Sean Christopherson [this message]
2021-05-17 18:15 ` Jim Mattson
2021-05-17 18:34 ` Sean Christopherson
2021-05-19 22:44 ` Dave Hansen
2021-05-19 23:15 ` Andy Lutomirski
2021-05-17 13:54 ` Dave Hansen
2021-05-17 16:43 ` Paolo Bonzini
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