From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, kvm <kvm@vger.kernel.org>,
Joel Schopp <joel.schopp@amd.com>
Subject: Re: [PATCH v2] KVM: SVM: Sync g_pat with guest-written PAT value
Date: Tue, 21 Apr 2015 14:21:49 +0200 [thread overview]
Message-ID: <20150421122148.GA15983@potion.brq.redhat.com> (raw)
In-Reply-To: <55362FFC.1040905@redhat.com>
2015-04-21 13:09+0200, Paolo Bonzini:
>
>
> On 20/04/2015 19:25, Jan Kiszka wrote:
> > When hardware supports the g_pat VMCB field, we can use it for emulating
> > the PAT configuration that the guest configures by writing to the
> > corresponding MSR.
> >
> > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>
> I'm not sure about this. The problem is that, unlike Intel, AMD has no
> way for the host to force its PAT value and ignore the guest's. I'm
> worried about potential performance problems in the guest.
We already set g_pat to 0x0007040600070406ULL in init_vmcb().
This patch uses caching that the guest expects, which might improve
performance as well. I think it's a step in right direction even if we
somehow optimize cache coherent cases later.
next prev parent reply other threads:[~2015-04-21 12:21 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-13 5:16 KVM: How does is PAT emulation supposed to work? Jan Kiszka
2015-04-13 6:58 ` [RFC][PATCH] KVM: SVM: Sync g_pat with guest-written PAT value Jan Kiszka
2015-04-17 16:59 ` Radim Krčmář
2015-04-20 16:14 ` Radim Krčmář
2015-04-20 17:16 ` Radim Krčmář
2015-04-20 17:21 ` Jan Kiszka
2015-04-20 17:33 ` Radim Krčmář
2015-04-20 17:37 ` Jan Kiszka
2015-04-20 17:45 ` Jan Kiszka
2015-04-20 18:33 ` Radim Krčmář
2015-04-20 18:41 ` Jan Kiszka
2015-04-21 12:10 ` Radim Krčmář
2015-04-21 12:11 ` Paolo Bonzini
2015-04-20 17:22 ` Radim Krčmář
2015-04-20 17:25 ` [PATCH v2] " Jan Kiszka
2015-04-20 17:35 ` Radim Krčmář
2015-04-21 11:09 ` Paolo Bonzini
2015-04-21 11:25 ` Jan Kiszka
2015-04-21 11:32 ` Paolo Bonzini
2015-04-21 11:56 ` Jan Kiszka
2015-04-21 12:12 ` Paolo Bonzini
2015-04-21 12:21 ` Radim Krčmář [this message]
2015-05-24 15:28 ` Jan Kiszka
2016-02-09 19:25 ` Jan Kiszka
2015-04-17 16:43 ` KVM: How does is PAT emulation supposed to work? Radim Krčmář
2015-04-17 17:12 ` Jan Kiszka
2015-04-17 20:28 ` Radim Krčmář
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