From: "Andersen, John S" <john.s.andersen@intel.com>
To: "liran.alon@oracle.com" <liran.alon@oracle.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "jmattson@google.com" <jmattson@google.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"bp@alien8.de" <bp@alien8.de>, "x86@kernel.org" <x86@kernel.org>,
"vkuznets@redhat.com" <vkuznets@redhat.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
"wanpengli@tencent.com" <wanpengli@tencent.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RESEND RFC 0/2] Paravirtualized Control Register pinning
Date: Mon, 23 Dec 2019 17:27:04 +0000 [thread overview]
Message-ID: <26f2b7e58fd45eede50f845a57761d1f01aff3f7.camel@intel.com> (raw)
In-Reply-To: <15b57d6b-0f46-01f5-1f75-b9b55db0611a@redhat.com>
On Mon, 2019-12-23 at 18:09 +0100, Paolo Bonzini wrote:
> On 23/12/19 15:48, Liran Alon wrote:
> > > Should userspace expose the CR pining CPUID feature bit, it must
> > > zero CR
> > > pinned MSRs on reboot. If it does not, it runs the risk of having
> > > the
> > > guest enable pinning and subsequently cause general protection
> > > faults on
> > > next boot due to early boot code setting control registers to
> > > values
> > > which do not contain the pinned bits.
> >
> > Why reset CR pinned MSRs by userspace instead of KVM INIT handling?
>
> Most MSRs are not reset by INIT, are they?
>
As far as I can tell, KVM doesn't know if the guest is rebooted.
Userspace uses the sregs and set MSRs ioctls to reset state.
kvm_vcpu_reset is called on non-boot CPUs. kvm_vcpu_init isn't called
on reboot.
next prev parent reply other threads:[~2019-12-23 17:27 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-20 19:26 [RESEND RFC 0/2] Paravirtualized Control Register pinning John Andersen
2019-12-20 19:27 ` [RESEND RFC 1/2] KVM: X86: Add CR pin MSRs John Andersen
2019-12-20 19:27 ` [RESEND RFC 2/2] X86: Use KVM " John Andersen
2019-12-23 7:39 ` Andy Lutomirski
2019-12-23 12:06 ` Borislav Petkov
2019-12-24 21:18 ` Andersen, John S
2019-12-24 6:45 ` kbuild test robot
2019-12-21 13:59 ` [RESEND RFC 0/2] Paravirtualized Control Register pinning Paolo Bonzini
2019-12-23 17:28 ` Andersen, John S
2019-12-23 14:30 ` Liran Alon
2019-12-24 22:56 ` Liran Alon
2019-12-25 2:04 ` Andy Lutomirski
2019-12-25 13:05 ` Liran Alon
2019-12-23 14:48 ` Liran Alon
2019-12-23 17:09 ` Paolo Bonzini
2019-12-23 17:27 ` Andersen, John S [this message]
2019-12-23 17:28 ` Liran Alon
2019-12-23 17:46 ` Paolo Bonzini
2019-12-23 22:49 ` Liran Alon
2019-12-24 19:44 ` Andersen, John S
2019-12-24 20:35 ` Liran Alon
2019-12-24 21:17 ` Andersen, John S
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