From: Chao Gao <chao.gao@intel.com>
To: Kai Huang <kai.huang@intel.com>
Cc: <seanjc@google.com>, <pbonzini@redhat.com>, <kvm@vger.kernel.org>,
<thomas.lendacky@amd.com>, <nikunj@amd.com>, <bp@alien8.de>,
<isaku.yamahata@intel.com>, <xiaoyao.li@intel.com>,
<rick.p.edgecombe@intel.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] KVM: x86: Reject KVM_SET_TSC_KHZ VM ioctl when vCPUs have been created
Date: Mon, 14 Jul 2025 16:44:15 +0800 [thread overview]
Message-ID: <aHTDX1IQuyWYUwL+@intel.com> (raw)
In-Reply-To: <135a35223ce8d01cea06b6cef30bfe494ec85827.1752444335.git.kai.huang@intel.com>
On Mon, Jul 14, 2025 at 10:20:19AM +1200, Kai Huang wrote:
>Reject the KVM_SET_TSC_KHZ VM ioctl when vCPUs have been created and
>update the documentation to reflect it.
>
>The VM scope KVM_SET_TSC_KHZ ioctl is used to set up the default TSC
>frequency that all subsequently created vCPUs can use. It is only
>intended to be called before any vCPU is created. Allowing it to be
>called after that only results in confusion but nothing good.
>
>Note this is an ABI change. But currently in Qemu (the de facto
>userspace VMM) only TDX uses this VM ioctl, and it is only called once
>before creating any vCPU, therefore the risk of breaking userspace is
>pretty low.
>
>Suggested-by: Sean Christopherson <seanjc@google.com>
>Signed-off-by: Kai Huang <kai.huang@intel.com>
>Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
next prev parent reply other threads:[~2025-07-14 8:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-13 22:20 [PATCH v2 0/2] Improve KVM_SET_TSC_KHZ handling for CoCo VMs Kai Huang
2025-07-13 22:20 ` [PATCH v2 1/2] KVM: x86: Reject KVM_SET_TSC_KHZ VM ioctl when vCPUs have been created Kai Huang
2025-07-14 5:43 ` Nikunj A. Dadhania
2025-07-14 8:44 ` Chao Gao [this message]
2025-07-13 22:20 ` [PATCH v2 2/2] KVM: x86: Reject KVM_SET_TSC_KHZ vCPU ioctl for TSC protected guest Kai Huang
2025-07-15 0:23 ` [PATCH v2 0/2] Improve KVM_SET_TSC_KHZ handling for CoCo VMs Sean Christopherson
2025-07-15 0:54 ` Huang, Kai
2025-07-15 14:07 ` Sean Christopherson
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