linux-kernel - Re: [PATCH v2 0/2] Improve KVM_SET_TSC

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Message-ID: <aHZghtaRrcfX7p5d@google.com>
Date: Tue, 15 Jul 2025 07:07:02 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Kai Huang <kai.huang@...el.com>
Cc: "pbonzini@...hat.com" <pbonzini@...hat.com>, Chao Gao <chao.gao@...el.com>, 
	Rick P Edgecombe <rick.p.edgecombe@...el.com>, "bp@...en8.de" <bp@...en8.de>, 
	Xiaoyao Li <xiaoyao.li@...el.com>, "nikunj@....com" <nikunj@....com>, 
	"thomas.lendacky@....com" <thomas.lendacky@....com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, 
	Isaku Yamahata <isaku.yamahata@...el.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/2] Improve KVM_SET_TSC_KHZ handling for CoCo VMs

On Tue, Jul 15, 2025, Kai Huang wrote:
> On Mon, 2025-07-14 at 17:23 -0700, Sean Christopherson wrote:
> > On Mon, 14 Jul 2025 10:20:18 +1200, Kai Huang wrote:
> > > This series follows Sean's suggestions [1][2] to:
> > > 
> > >  - Reject vCPU scope KVM_SET_TSC_KHZ ioctl for TSC protected vCPU
> > >  - Reject VM scope KVM_SET_TSC_KHZ ioctl when vCPUs have been created
> > > 
> > > .. in the discussion of SEV-SNP Secure TSC support series.
> > > 
> > > [...]
> > 
> > Applied patch 2 to kvm-x86 fixes, with a tweaked changelog to call out that
> > TDX support hasn't yet been released, i.e. that there is no established ABI
> > to break.
> > 
> > Applied patch 1 to kvm-x86 misc, with tweaked documentation to not imply that
> > userspace "must" invoke the ioctl.  I think this is the last patch I'll throw
> > into misc for 6.17?  So in theory, if it breaks userspace, I can simply
> > truncate it from the pull request.
> 
> Thanks!
> 
> > 
> > [1/2] KVM: x86: Reject KVM_SET_TSC_KHZ VM ioctl when vCPUs have been created
> >       https://github.com/kvm-x86/linux/commit/dcbe5a466c12
> > [2/2] KVM: x86: Reject KVM_SET_TSC_KHZ vCPU ioctl for TSC protected guest
> >       https://github.com/kvm-x86/linux/commit/e51cf184d90c
> 
> Btw, in the second patch it seems you have:
> 
>   Fixes; adafea1 ("KVM: x86: Add infrastructure for secure TSC")
> 
> Shouldn't we follow the standard format, i.e.,
> 
>   Fixes: adafea110600 ("KVM: x86: Add infrastructure for secure TSC")

Ugh, yes, the semi-colon is just a typo.  New hash:

  https://github.com/kvm-x86/linux/commit/b24bbb534c2d