From: "Huang, Kai" <kai.huang@intel.com>
To: "tglx@linutronix.de" <tglx@linutronix.de>,
"peterz@infradead.org" <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"Hansen, Dave" <dave.hansen@intel.com>,
"bp@alien8.de" <bp@alien8.de>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"seanjc@google.com" <seanjc@google.com>,
"x86@kernel.org" <x86@kernel.org>,
"sagis@google.com" <sagis@google.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"Chatre, Reinette" <reinette.chatre@intel.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"Yamahata, Isaku" <isaku.yamahata@intel.com>,
"ashish.kalra@amd.com" <ashish.kalra@amd.com>,
"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
"nik.borisov@suse.com" <nik.borisov@suse.com>
Subject: Re: [PATCH v2.1 2/5] x86/virt/tdx: Mark memory cache state incoherent when making SEAMCALL
Date: Wed, 14 May 2025 22:13:54 +0000 [thread overview]
Message-ID: <489d219318944a7fd0bb7ebe6a58835943a9d684.camel@intel.com> (raw)
In-Reply-To: <66f5b7f0-8109-4c10-80ef-783ba8bccae6@intel.com>
On Wed, 2025-05-14 at 08:52 -0700, Hansen, Dave wrote:
> On 5/14/25 03:10, Kai Huang wrote:
> > Turn on that boolean when the kernel does SEAMCALL so that kexec can
> > correctly flush cache. Note not all SEAMCALL leaf functions generate
> > dirty cachelines of TDX private memory, but for simplicity, just treat
> > all of them do.
>
> It's not just for simplicity.
>
> There's no contract in place for when the TDX module will dirty memory
> or not. A call that is "clean" today might dirty memory tomorrow.
>
> The _only_ thing we know is that SEAMCALLs can dirty cachelines. We
> don't know when or how they do it. This blurb makes it sound like it's
> possible to optimize this. It's not.
I thought it should not be possible to generate dirty cachelines with TDX
private KeyIDs before the very first TDX KeyID (which is global KeyID) is
configured, but right I guess we'd better not assume that.
I'll remote the "Note ..." part. Thanks!
next prev parent reply other threads:[~2025-05-14 22:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-10 11:20 [PATCH v2 0/5] TDX host: kexec/kdump support Kai Huang
2025-05-10 11:20 ` [PATCH v2 1/5] x86/sme: Use percpu boolean to control wbinvd during kexec Kai Huang
2025-05-10 11:20 ` [PATCH v2 2/5] x86/virt/tdx: Mark memory cache state incoherent when making SEAMCALL Kai Huang
2025-05-14 10:10 ` [PATCH v2.1 " Kai Huang
2025-05-14 15:52 ` Dave Hansen
2025-05-14 22:13 ` Huang, Kai [this message]
2025-05-10 11:20 ` [PATCH v2 3/5] x86/kexec: Disable kexec/kdump on platforms with TDX partial write erratum Kai Huang
2025-05-10 11:20 ` [PATCH v2 4/5] x86/virt/tdx: Remove the !KEXEC_CORE dependency Kai Huang
2025-05-10 11:20 ` [PATCH v2 5/5] x86/virt/tdx: Update the kexec section in the TDX documentation Kai Huang
2025-05-10 11:25 ` [RFC PATCH v2 6/5] KVM: TDX: Explicitly do WBINVD upon reboot notifier Kai Huang
2025-06-13 11:36 ` Paolo Bonzini
2025-06-16 10:39 ` Huang, Kai
2025-05-14 12:37 ` [PATCH v2 0/5] TDX host: kexec/kdump support Tom Lendacky
2025-05-14 22:09 ` Huang, Kai
2025-05-29 11:06 ` Huang, Kai
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