From: Jim Mattson <jmattson@google.com>
To: stsp <stsp2@yandex.ru>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: X86: Fix exception untrigger on ret to user
Date: Mon, 28 Jun 2021 09:39:39 -0700 [thread overview]
Message-ID: <CALMp9eRJedCx6AMW+gMBMeMvGRzn6uzB0wtAzTDRLdYMB1Kc5Q@mail.gmail.com> (raw)
In-Reply-To: <17c7da34-7a54-017e-1c2f-870d7e2c5ed7@yandex.ru>
On Mon, Jun 28, 2021 at 4:27 AM stsp <stsp2@yandex.ru> wrote:
>
> 28.06.2021 13:56, Vitaly Kuznetsov пишет:
> > stsp <stsp2@yandex.ru> writes:
> >
> >> Yes, cancel_injection is supposed to
> >> be always broken indeed. But there
> >> are a few more things to it.
> >> Namely:
> >> - Other CPUs do not seem to exhibit
> >> that path. My guess here is that they
> >> just handle the exception in hardware,
> >> without returning to KVM for that. I
> >> am not sure why Core2 vmexits per
> >> each page fault. Is it incapable of
> >> handling the PF in hardware, or maybe
> >> some other bug is around?
> > Wild guess: no EPT support and running on shadow pages?
>
> That's something you should tell
> me, and not the other way around. :)
> I am just working with kvm as a user.
>
Yes, with shadow paging, kvm intercepts all guest page faults. You
should be able to replicate this behavior on modern CPUs by adding
"ept=N" to the kvm_intel module parameters.
next prev parent reply other threads:[~2021-06-28 16:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-27 23:38 [PATCH] KVM: X86: Fix exception untrigger on ret to user Stas Sergeev
2021-06-28 7:20 ` Vitaly Kuznetsov
2021-06-28 9:12 ` stsp
2021-06-28 10:07 ` Vitaly Kuznetsov
2021-06-28 10:32 ` stsp
2021-06-28 10:56 ` Vitaly Kuznetsov
2021-06-28 11:00 ` Vitaly Kuznetsov
2021-06-28 11:27 ` stsp
2021-06-28 16:39 ` Jim Mattson [this message]
2021-06-28 16:57 ` stsp
2021-06-28 16:19 ` Jim Mattson
2021-06-28 17:06 ` stsp
2021-06-28 17:44 ` Jim Mattson
2021-06-28 22:23 ` stsp
2021-06-28 22:35 ` Jim Mattson
2021-06-28 22:52 ` stsp
2021-06-28 12:46 Stas Sergeev
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