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From: Brijesh Singh <brijesh.singh@amd.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Cc: <brijesh.singh@amd.com>, <joro@8bytes.org>, <kvm@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <tglx@linutronix.de>,
	<mingo@redhat.com>, <hpa@zytor.com>, <x86@kernel.org>,
	<Thomas.Lendacky@amd.com>
Subject: Re: [PATCH] x86: kvm: Avoid guest page table walk when gpa_available is set
Date: Tue, 2 May 2017 16:44:19 -0500	[thread overview]
Message-ID: <99ec8226-07c0-7d10-5659-52c647de0d19@amd.com> (raw)
In-Reply-To: <c57e0bae-c4db-c19b-7727-3695cacd5ba9@redhat.com>

Hi Paolo,

>>
>> I've tried the below patch and it seems to work fine. This does not
>> consider
>> PIO case and as you rightly pointed PIO should trigger #NPF relatively
>> rarely.
>> At least so far in my runs I have not seen PIO causing #NPF. If this sounds
>> acceptable approach then I can submit v2 with these changes and remove
>> gpa_val
>> additional.
>
> PIO can certainly cause #NPF, albeit rarely, so this is not a viable one.
>

For SEV guest cases, we anyway want to avoid any guest page table walks
(even if it happens rarely). Sounds like we have to depend on gpa_val variable.
I will refresh the patch to address one of Ramdim's feedback
(move vcpu->arch.gpa_val assignment from handle_exit to pf_interception).

Brijesh

      reply	other threads:[~2017-05-02 21:44 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-24 15:52 [PATCH] x86: kvm: Avoid guest page table walk when gpa_available is set Brijesh Singh
2017-04-24 16:16 ` Brijesh Singh
2017-04-24 20:52 ` Radim Krčmář
2017-04-24 22:14   ` Brijesh Singh
2017-04-25 14:03     ` Radim Krčmář
2017-04-25 22:02       ` Brijesh Singh
2017-04-26 20:44         ` Radim Krčmář
2017-04-28 19:15           ` Brijesh Singh
2017-05-02 16:24             ` Paolo Bonzini
2017-05-02 21:44               ` Brijesh Singh [this message]

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