From: Sean Christopherson <seanjc@google.com>
To: Chao Gao <chao.gao@intel.com>
Cc: linux-coco@lists.linux.dev, x86@kernel.org, kvm@vger.kernel.org,
paulmck@kernel.org, pbonzini@redhat.com, eddie.dong@intel.com,
kirill.shutemov@intel.com, dave.hansen@intel.com,
dan.j.williams@intel.com, kai.huang@intel.com,
isaku.yamahata@intel.com, elena.reshetova@intel.com,
rick.p.edgecombe@intel.com, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC PATCH 00/20] TD-Preserving updates
Date: Fri, 11 Jul 2025 07:06:21 -0700 [thread overview]
Message-ID: <aHEaXYmeolKNCqgk@google.com> (raw)
In-Reply-To: <aHDFoIvB5+33blGp@intel.com>
On Fri, Jul 11, 2025, Chao Gao wrote:
> >2. P-SEAMLDR seamcalls (specificially SEAMRET from P-SEAMLDR) clear current
> > VMCS pointers, which may disrupt KVM. To prevent VMX instructions in IRQ
> > context from encountering NULL current-VMCS pointers, P-SEAMLDR
> > seamcalls are called with IRQ disabled. I'm uncertain if NMIs could
> > cause a problem, but I believe they won't. See more information in patch 3.
NMIs shouldn't be a problem. KVM does access the current VMCS in NMI context
(to do VMREAD(GUEST_RIP) in response to a perf NMI), but only when KVM knows the
NMI occurred in KVM's run loop. So in effect, only in KVM_RUN context, which I
gotta image is mutually exclusive with tdx_fw_write().
It'd be nice if we could make the P-SEAMLDR calls completely NMI safe, but
practically speaking, if KVM (or any other hypervisor) is playing with the VMCS
in arbitrary NMI handlers, then we've probably got bigger issues.
next prev parent reply other threads:[~2025-07-11 14:06 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-23 9:52 [RFC PATCH 00/20] TD-Preserving updates Chao Gao
2025-05-23 9:52 ` [RFC PATCH 01/20] x86/virt/tdx: Print SEAMCALL leaf numbers in decimal Chao Gao
2025-06-02 23:44 ` Huang, Kai
2025-05-23 9:52 ` [RFC PATCH 02/20] x86/virt/tdx: Prepare to support P-SEAMLDR SEAMCALLs Chao Gao
2025-06-04 12:22 ` Huang, Kai
2025-06-04 13:14 ` Chao Gao
2025-06-05 0:14 ` Huang, Kai
2025-05-23 9:52 ` [RFC PATCH 03/20] x86/virt/seamldr: Introduce a wrapper for " Chao Gao
2025-06-03 11:22 ` Nikolay Borisov
2025-06-09 7:53 ` Chao Gao
2025-06-09 8:02 ` Nikolay Borisov
2025-06-10 1:03 ` Chao Gao
2025-06-10 6:52 ` Nikolay Borisov
2025-06-10 15:02 ` Dave Hansen
2025-07-11 13:59 ` Sean Christopherson
2025-07-14 9:21 ` Chao Gao
2025-05-23 9:52 ` [RFC PATCH 04/20] x86/virt/tdx: Introduce a "tdx" subsystem and "tsm" device Chao Gao
2025-06-02 23:44 ` Huang, Kai
2025-06-05 8:34 ` Chao Gao
2025-07-31 20:17 ` dan.j.williams
2025-05-23 9:52 ` [RFC PATCH 05/20] x86/virt/tdx: Export tdx module attributes via sysfs Chao Gao
2025-06-02 23:49 ` Huang, Kai
2025-06-10 1:37 ` Chao Gao
2025-06-11 2:09 ` Huang, Kai
2025-06-11 7:45 ` Chao Gao
2025-05-23 9:52 ` [RFC PATCH 06/20] x86/virt/seamldr: Add a helper to read P-SEAMLDR information Chao Gao
2025-05-23 9:52 ` [RFC PATCH 07/20] x86/virt/tdx: Expose SEAMLDR information via sysfs Chao Gao
2025-07-29 4:55 ` Xu Yilun
2025-07-29 10:00 ` Chao Gao
2025-07-31 21:01 ` dan.j.williams
2025-08-01 2:07 ` Xu Yilun
2025-08-01 15:24 ` dan.j.williams
2025-08-04 7:00 ` Xu Yilun
2025-08-05 0:17 ` dan.j.williams
2025-08-05 0:47 ` Sean Christopherson
2025-08-05 4:02 ` dan.j.williams
2025-08-05 13:49 ` Sean Christopherson
2025-08-06 16:33 ` dan.j.williams
2025-08-06 3:03 ` Xu Yilun
2025-05-23 9:52 ` [RFC PATCH 08/20] x86/virt/seamldr: Implement FW_UPLOAD sysfs ABI for TD-Preserving Updates Chao Gao
2025-06-16 22:55 ` Sagi Shahar
2025-06-17 7:55 ` Chao Gao
2025-05-23 9:52 ` [RFC PATCH 09/20] x86/virt/seamldr: Allocate and populate a module update request Chao Gao
2025-05-23 9:52 ` [RFC PATCH 10/20] x86/virt/seamldr: Introduce skeleton for TD-Preserving updates Chao Gao
2025-05-23 9:52 ` [RFC PATCH 11/20] x86/virt/seamldr: Abort updates if errors occurred midway Chao Gao
2025-06-03 12:04 ` Nikolay Borisov
2025-06-09 2:37 ` Chao Gao
2025-05-23 9:52 ` [RFC PATCH 12/20] x86/virt/seamldr: Shut down the current TDX module Chao Gao
2025-06-03 12:36 ` Nikolay Borisov
2025-06-09 2:10 ` Chao Gao
2025-05-23 9:52 ` [RFC PATCH 13/20] x86/virt/tdx: Reset software states after TDX module shutdown Chao Gao
2025-05-23 9:52 ` [RFC PATCH 14/20] x86/virt/seamldr: Install a new TDX module Chao Gao
2025-05-23 9:52 ` [RFC PATCH 15/20] x86/virt/seamldr: Handle TD-Preserving update failures Chao Gao
2025-05-23 9:52 ` [RFC PATCH 16/20] x86/virt/seamldr: Do TDX cpu init after updates Chao Gao
2025-05-23 9:52 ` [RFC PATCH 17/20] x86/virt/tdx: Establish contexts for the new module Chao Gao
2025-05-23 9:52 ` [RFC PATCH 18/20] x86/virt/tdx: Update tdx_sysinfo and check features post-update Chao Gao
2025-05-23 9:52 ` [RFC PATCH 19/20] x86/virt/seamldr: Verify availability of slots for TD-Preserving updates Chao Gao
2025-05-23 9:52 ` [RFC PATCH 20/20] x86/virt/seamldr: Enable TD-Preserving Updates Chao Gao
2025-06-11 19:56 ` [RFC PATCH 00/20] TD-Preserving updates Sagi Shahar
2025-07-11 8:04 ` Chao Gao
2025-07-11 14:06 ` Sean Christopherson [this message]
2025-07-14 10:26 ` Chao Gao
2025-07-15 0:21 ` Paul E. McKenney
2025-07-16 7:30 ` Chao Gao
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