From: Yan Zhao <yan.y.zhao@intel.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Kirill A. Shutemov" <kas@kernel.org>, <kvm@vger.kernel.org>,
<x86@kernel.org>, <linux-coco@lists.linux.dev>,
<linux-kernel@vger.kernel.org>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Hou Wenlong <houwenlong.hwl@antgroup.com>
Subject: Re: [PATCH v5 1/4] KVM: TDX: Explicitly set user-return MSRs that *may* be clobbered by the TDX-Module
Date: Tue, 4 Nov 2025 17:31:08 +0800 [thread overview]
Message-ID: <aQnH3EmN97cAKDEO@yzhao56-desk.sh.intel.com> (raw)
In-Reply-To: <969d1b3a-2a82-4ff1-85c5-705c102f0f8b@intel.com>
On Tue, Nov 04, 2025 at 04:40:44PM +0800, Xiaoyao Li wrote:
> On 11/4/2025 3:06 PM, Yan Zhao wrote:
> > Another nit:
> > Remove the tdx_user_return_msr_update_cache() in the comment of __tdx_bringup().
> >
> > Or could we just invoke tdx_user_return_msr_update_cache() in
> > tdx_prepare_switch_to_guest()?
>
> No. It lacks the WRMSR operation to update the hardware value, which is the
> key of this patch.
As [1], I don't think the WRMSR operation to update the hardware value is
necessary. The value will be updated to guest value soon any way if
tdh_vp_enter() succeeds, or the hardware value remains to be the host value or
the default value.
But I think invoking tdx_user_return_msr_update_cache() in
tdx_prepare_switch_to_guest() is better than in
tdx_prepare_switch_to_host().
[1] https://lore.kernel.org/kvm/aQhJol0CvT6bNCJQ@yzhao56-desk.sh.intel.com/
next prev parent reply other threads:[~2025-11-04 9:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-30 19:15 [PATCH v5 0/4] KVM: x86: User-return MSR fix+cleanups Sean Christopherson
2025-10-30 19:15 ` [PATCH v5 1/4] KVM: TDX: Explicitly set user-return MSRs that *may* be clobbered by the TDX-Module Sean Christopherson
2025-11-03 6:20 ` Yan Zhao
2025-11-04 7:06 ` Yan Zhao
2025-11-04 8:40 ` Xiaoyao Li
2025-11-04 9:31 ` Yan Zhao [this message]
2025-11-04 17:55 ` Sean Christopherson
2025-11-05 1:52 ` Yan Zhao
2025-11-05 9:16 ` Xiaoyao Li
2025-11-06 2:22 ` Yan Zhao
2025-11-03 7:42 ` Xiaoyao Li
2025-10-30 19:15 ` [PATCH v5 2/4] KVM: x86: WARN if user-return MSR notifier is registered on exit Sean Christopherson
2025-10-30 19:15 ` [PATCH v5 3/4] KVM: x86: Leave user-return notifier registered on reboot/shutdown Sean Christopherson
2025-11-07 8:18 ` Chao Gao
2025-11-08 1:37 ` Sean Christopherson
2025-10-30 19:15 ` [PATCH v5 4/4] KVM: x86: Don't disable IRQs when unregistering user-return notifier Sean Christopherson
2025-11-04 10:34 ` Huang, Kai
2025-11-10 15:37 ` [PATCH v5 0/4] KVM: x86: User-return MSR fix+cleanups Sean Christopherson
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