From: Paul Durrant <xadimgnik@gmail.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
David Woodhouse <dwmw2@infradead.org>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+cdeaeec70992eca2d920@syzkaller.appspotmail.com,
Joao Martins <joao.m.martins@oracle.com>,
David Woodhouse <dwmw@amazon.co.uk>
Subject: Re: [PATCH 3/5] KVM: x86/xen: Consult kvm_xen_enabled when checking for Xen MSR writes
Date: Mon, 3 Feb 2025 09:15:06 +0000 [thread overview]
Message-ID: <2f4752d5-63ec-4e7f-bb7a-a97eecfdfb18@xen.org> (raw)
In-Reply-To: <20250201011400.669483-4-seanjc@google.com>
On 01/02/2025 01:13, Sean Christopherson wrote:
> Query kvm_xen_enabled when detecting writes to the Xen hypercall page MSR
> so that the check is optimized away in the likely scenario that Xen isn't
> enabled for the VM.
>
> Deliberately open code the check instead of using kvm_xen_msr_enabled() in
> order to avoid a double load of xen_hvm_config.msr (which is admittedly
> rather pointless given the widespread lack of READ_ONCE() usage on the
> plethora of vCPU-scoped accesses to kvm->arch.xen state).
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/xen.h | 3 +++
> 1 file changed, 3 insertions(+)
>
Reviewed-by: Paul Durrant <paul@xen.org>
next prev parent reply other threads:[~2025-02-03 9:15 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-01 1:13 [PATCH 0/5] KVM: x86/xen: Restrict hypercall MSR index Sean Christopherson
2025-02-01 1:13 ` [PATCH 1/5] KVM: x86/xen: Restrict hypercall MSR to unofficial synthetic range Sean Christopherson
2025-02-03 9:09 ` Paul Durrant
2025-02-05 9:27 ` David Woodhouse
2025-02-05 15:06 ` Sean Christopherson
2025-02-05 15:26 ` David Woodhouse
2025-02-05 15:51 ` Sean Christopherson
2025-02-05 16:18 ` David Woodhouse
2025-02-05 17:15 ` David Woodhouse
2025-02-05 19:20 ` Sean Christopherson
2025-02-06 18:58 ` David Woodhouse
2025-02-07 17:18 ` Sean Christopherson
2025-02-06 9:18 ` David Woodhouse
2026-04-28 14:54 ` David Woodhouse
2025-02-06 16:51 ` David Woodhouse
2025-02-01 1:13 ` [PATCH 2/5] KVM: x86/xen: Add an #ifdef'd helper to detect writes to Xen MSR Sean Christopherson
2025-02-03 9:09 ` Paul Durrant
2025-02-06 16:28 ` David Woodhouse
2025-02-01 1:13 ` [PATCH 3/5] KVM: x86/xen: Consult kvm_xen_enabled when checking for Xen MSR writes Sean Christopherson
2025-02-03 9:15 ` Paul Durrant [this message]
2025-02-06 16:29 ` David Woodhouse
2025-02-01 1:13 ` [PATCH 4/5] KVM: x86/xen: Bury xen_hvm_config behind CONFIG_KVM_XEN=y Sean Christopherson
2025-02-03 9:19 ` Paul Durrant
2025-02-06 16:30 ` David Woodhouse
2025-02-01 1:14 ` [PATCH 5/5] KVM: x86/xen: Move kvm_xen_hvm_config field into kvm_xen Sean Christopherson
2025-02-03 9:21 ` Paul Durrant
2025-02-06 16:32 ` David Woodhouse
2025-02-06 19:14 ` [PATCH] KVM: x86/xen: Only write Xen hypercall page for guest writes to MSR David Woodhouse
2025-02-15 0:50 ` Sean Christopherson
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