From: Dave Hansen <dave.hansen@intel.com>
To: Sean Christopherson <seanjc@google.com>,
Rick P Edgecombe <rick.p.edgecombe@intel.com>
Cc: Vishal L Verma <vishal.l.verma@intel.com>,
Kai Huang <kai.huang@intel.com>, "bp@alien8.de" <bp@alien8.de>,
"x86@kernel.org" <x86@kernel.org>,
"kas@kernel.org" <kas@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"tglx@kernel.org" <tglx@kernel.org>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 2/5] x86/virt/tdx: Pull kexec cache flush logic into arch/x86
Date: Wed, 1 Apr 2026 08:03:02 -0700 [thread overview]
Message-ID: <830f1e46-0fb7-4756-827b-c8f46af24374@intel.com> (raw)
In-Reply-To: <acxTBwaw6_xYSShf@google.com>
On 3/31/26 16:04, Sean Christopherson wrote:
> But unless the WBINVD is actually costly, why bother getting fancy?
WBINVD might be the most expensive single instruction in the whole ISA.
That said, I'd much rather have a potentially unnecessary WBINVD than
miss one. The thing I'd be worried about would be something wonky like:
1. CPU offline does WBINVD
2. Some other TDX call gets made, dirties caches again
3. tdx_offline_cpu() skips WBINVD
So, let's just do both for now: Do WBINVD in tdx_offline_cpu() and
comment that it might be redundant with other things in the CPU offline
procedure.
This really needs to be solved with infrastructure and keeping data
about the reasons for needing WBINVD, not relying on code ordering or
fragile semantics.
next prev parent reply other threads:[~2026-04-01 15:02 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-23 20:59 [PATCH v2 0/5] Fuller TDX kexec support Vishal Verma
2026-03-23 20:59 ` [PATCH v2 1/5] x86/tdx: Move all TDX error defines into <asm/shared/tdx_errno.h> Vishal Verma
2026-03-24 9:49 ` Chao Gao
2026-03-31 19:30 ` Sean Christopherson
2026-03-31 21:46 ` Edgecombe, Rick P
2026-03-23 20:59 ` [PATCH v2 2/5] x86/virt/tdx: Pull kexec cache flush logic into arch/x86 Vishal Verma
2026-03-24 10:03 ` Chao Gao
2026-03-30 11:42 ` Kiryl Shutsemau
2026-03-31 19:22 ` Sean Christopherson
2026-03-31 22:21 ` Edgecombe, Rick P
2026-03-31 23:04 ` Sean Christopherson
2026-03-31 23:29 ` Edgecombe, Rick P
2026-04-01 15:03 ` Dave Hansen [this message]
2026-04-01 17:42 ` H. Peter Anvin
2026-04-01 18:12 ` Sean Christopherson
2026-04-01 18:30 ` Dave Hansen
2026-03-23 20:59 ` [PATCH v2 3/5] x86/virt/tdx: Add SEAMCALL wrapper for TDH.SYS.DISABLE Vishal Verma
2026-03-23 21:54 ` Verma, Vishal L
2026-03-23 22:40 ` Huang, Kai
2026-03-24 10:18 ` Chao Gao
2026-03-30 11:58 ` Kiryl Shutsemau
2026-03-30 19:25 ` Edgecombe, Rick P
2026-03-31 12:18 ` Kiryl Shutsemau
2026-03-31 18:22 ` Verma, Vishal L
2026-03-31 21:36 ` Edgecombe, Rick P
2026-04-01 9:26 ` Kiryl Shutsemau
2026-04-01 14:24 ` Dave Hansen
2026-03-23 20:59 ` [PATCH v2 4/5] x86/tdx: Disable the TDX module during kexec and kdump Vishal Verma
2026-03-23 22:41 ` Huang, Kai
2026-03-30 12:03 ` Kiryl Shutsemau
2026-03-23 20:59 ` [PATCH v2 5/5] x86/virt/tdx: Remove kexec docs Vishal Verma
2026-03-23 22:41 ` Huang, Kai
2026-03-30 12:04 ` Kiryl Shutsemau
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