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From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "binbin.wu@linux.intel.com" <binbin.wu@linux.intel.com>,
	"thorsten.blum@linux.dev" <thorsten.blum@linux.dev>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"seanjc@google.com" <seanjc@google.com>,
	"kas@kernel.org" <kas@kernel.org>
Subject: Re: [PATCH] KVM: x86: TDX: Use validated CPUID entry count for TD init
Date: Wed, 8 Jul 2026 16:20:40 +0000	[thread overview]
Message-ID: <28ec0a5ac5c46448df5983cc7f9cbc71f6014e8a.camel@intel.com> (raw)
In-Reply-To: <315e969a-4ab1-433e-91c5-2308f1975281@linux.intel.com>

On Wed, 2026-07-08 at 17:04 +0800, Binbin Wu wrote:
> > Maybe it would be better to check for a mismatch and return -EINVAL?
> > 
> >  	if (init_vm->cpuid.nent != nr_user_entries) {
> >  		ret = -EINVAL;
> >  		goto out;
> >  	}
> > 
> > That would make the mismatch explicit instead of silently accepting an
> > inconsistent userspace snapshot.
> 
> I chose to use the snapshot value to follow KVM_SET_CPUID2's style.
> KVM_SET_CPUID2 kind of uses the snapshot value of entry count.
> 
> But returning a error code is OK for me.
> Let's wait and see what others prefer.

It does seem safer to reject input than have some implicit behavior.

  reply	other threads:[~2026-07-08 16:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-08  2:29 [PATCH] KVM: x86: TDX: Use validated CPUID entry count for TD init Binbin Wu
2026-07-08  8:42 ` Thorsten Blum
2026-07-08  9:04   ` Binbin Wu
2026-07-08 16:20     ` Edgecombe, Rick P [this message]
2026-07-09  1:50       ` Binbin Wu
2026-07-09 13:41         ` Sean Christopherson

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