From: Paolo Bonzini <pbonzini@redhat.com>
To: Lai Jiangshan <laijs@linux.alibaba.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-kernel@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH V2 2/3] KVM: X86: Set the hardware DR6 only when KVM_DEBUGREG_WONT_EXIT
Date: Tue, 10 Aug 2021 14:49:54 +0200 [thread overview]
Message-ID: <ffbc18d0-aeca-ce0e-5bb8-612e7f5800d1@redhat.com> (raw)
In-Reply-To: <7f86316b-5010-5250-4223-5a4d62f942c8@linux.alibaba.com>
On 10/08/21 12:46, Lai Jiangshan wrote:
> I'm OK with it. But I don't think the sketched idea would cause DR6 to
> be marked uselessly as dirty in SVM. It doesn't mark it dirty if the
> value is unchanged, and the value is always DR6_ACTIVE_LOW except when
> it just clears KVM_DEBUGREG_WONT_EXIT.
It would be marked dirty if it is not DR6_ACTIVE_LOW, because it would
be set first to DR6_ACTIVE_LOW in svm_handle_exit and then set back to
the guest value on the next entry.
Paolo
next prev parent reply other threads:[~2021-08-10 12:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-08 23:29 [PATCH] KVM: X86: Don't reset dr6 unconditionally when the vcpu being scheduled out Lai Jiangshan
2021-08-09 16:54 ` Sean Christopherson
2021-08-09 17:43 ` [PATCH V2 1/3] KVM: X86: Remove unneeded KVM_DEBUGREG_RELOAD Lai Jiangshan
2021-08-09 17:43 ` [PATCH V2 2/3] KVM: X86: Set the hardware DR6 only when KVM_DEBUGREG_WONT_EXIT Lai Jiangshan
2021-08-10 10:07 ` Paolo Bonzini
2021-08-10 10:30 ` Lai Jiangshan
2021-08-10 10:35 ` Paolo Bonzini
2021-08-10 10:46 ` Lai Jiangshan
2021-08-10 12:49 ` Paolo Bonzini [this message]
2021-08-09 17:43 ` [PATCH V2 3/3] KVM: X86: Reset " Lai Jiangshan
2021-08-10 9:42 ` Paolo Bonzini
2021-08-10 10:14 ` Paolo Bonzini
2021-08-10 10:34 ` Lai Jiangshan
2021-08-10 10:41 ` Paolo Bonzini
2021-08-10 9:59 ` [PATCH] KVM: X86: Don't reset dr6 unconditionally when the vcpu being scheduled out Paolo Bonzini
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