From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Joel Schopp <joel.schopp@amd.com>
Cc: Gleb Natapov <gleb@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org, David Kaplan <david.kaplan@amd.com>
Subject: Re: [PATCH] kvm: x86: svm: remove SVM_EXIT_READ_CR* intercepts
Date: Thu, 12 Mar 2015 22:20:02 +0100 [thread overview]
Message-ID: <20150312212002.GA1711@potion.brq.redhat.com> (raw)
In-Reply-To: <20150312201746.2953.11716.stgit@joelvm2.amd.com>
2015-03-12 15:17-0500, Joel Schopp:
> There isn't really a valid reason for kvm to intercept cr* reads
> on svm hardware. The current kvm code just ends up returning
> the register
There is no need to intercept CR* if the value that the guest should see
is equal to what we set there, but that is not always the case:
- CR0 might differ from what the guest should see because of lazy fpu
- CR3 isn't intercepted with nested paging and it should differ
otherwise
- CR4 contains PAE bit when run without nested paging
CR2 and CR8 already aren't intercepted, so it looks like only CR0 and
CR4 could use some optimizations.
next prev parent reply other threads:[~2015-03-12 21:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-12 20:17 [PATCH] kvm: x86: svm: remove SVM_EXIT_READ_CR* intercepts Joel Schopp
2015-03-12 21:17 ` Bandan Das
2015-04-03 12:19 ` Radim Krčmář
2015-03-12 21:20 ` Radim Krčmář [this message]
2015-03-16 16:16 ` Joel Schopp
2015-03-16 17:34 ` Radim Krčmář
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