From: Paolo Bonzini <pbonzini@redhat.com>
To: Bandan Das <bsd@redhat.com>, kvm@vger.kernel.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
Gleb Natapov <gleb@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/3] KVM: x86: use memory_prepare in fetch helper function
Date: Tue, 06 May 2014 11:46:02 +0200 [thread overview]
Message-ID: <5368AF5A.2090905@redhat.com> (raw)
In-Reply-To: <1399336859-7227-3-git-send-email-bsd@redhat.com>
Il 06/05/2014 02:40, Bandan Das ha scritto:
> + ret = ctxt->ops->memory_prepare(ctxt, addr, toread,
> + exception, false,
> + NULL, &uaddr);
> + if (ret != X86EMUL_CONTINUE)
> + return ret;
> +
> + if (unlikely(kvm_is_error_hva(uaddr))) {
> + r = X86EMUL_PROPAGATE_FAULT;
> + return r;
> + }
What you are doing here is basically optimizing
kvm_read_guest_virt_helper because you know that all reads will be
single-page and you do not need the "next_segment" in kvm_read_guest.
Good catch, but you can use kvm_read_guest_page instead of going through
ctxt->ops->memory_prepare. :)
Paolo
> + ret = __copy_from_user(data, (void __user *)uaddr, toread);
next prev parent reply other threads:[~2014-05-06 9:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-06 0:40 [RFC PATCH 0/3] Emulator Speedups - Optimize Instruction fetches Bandan Das
2014-05-06 0:40 ` [RFC PATCH 1/3] KVM: x86: pass ctxt to fetch helper function Bandan Das
2014-05-06 0:40 ` [RFC PATCH 2/3] KVM: x86: use memory_prepare in " Bandan Das
2014-05-06 8:27 ` Paolo Bonzini
2014-05-06 9:46 ` Paolo Bonzini [this message]
2014-05-06 0:40 ` [RFC PATCH 3/3] KVM: x86: cache userspace address for faster fetches Bandan Das
2014-05-06 9:40 ` Paolo Bonzini
2014-05-07 4:45 ` Bandan Das
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