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

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Message-ID: <cover.1752444335.git.kai.huang@intel.com>
Date: Mon, 14 Jul 2025 10:20:18 +1200
From: Kai Huang <kai.huang@...el.com>
To: seanjc@...gle.com,
	pbonzini@...hat.com
Cc: kvm@...r.kernel.org,
	thomas.lendacky@....com,
	nikunj@....com,
	bp@...en8.de,
	isaku.yamahata@...el.com,
	xiaoyao.li@...el.com,
	rick.p.edgecombe@...el.com,
	chao.gao@...el.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/2] Improve KVM_SET_TSC_KHZ handling for CoCo VMs

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.

v1 -> v2:
 - Protect kvm->create_vcpus check using kvm->lock. - Chao.
 - Add documentation update to each patch.  -Nikunj.
 - Collect RB (Xiaoyao, Nikunj).
 - Switched the patch order to make documentation update easier.

 v1: https://lore.kernel.org/kvm/cover.1752038725.git.kai.huang@intel.com/

Hi Xiaoyao, Nikunj, I added your RB anyway, so let me know if you have
concern :-)

This series has been sanity tested with TDX guests using today's Qemu:

 - With this series Qemu can still run TDX guests successfully.
 - With some hack to the Qemu, both VM and vCPU scope KVM_SET_TSC_KHZ
   ioctls failed as expected.

Kai Huang (2):
  KVM: x86: Reject KVM_SET_TSC_KHZ VM ioctl when vCPUs have been created
  KVM: x86: Reject KVM_SET_TSC_KHZ vCPU ioctl for TSC protected guest

 Documentation/virt/kvm/api.rst |  9 ++++++++-
 arch/x86/kvm/x86.c             | 13 ++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)


base-commit: 6c7ecd725e503bf2ca69ff52c6cc48bb650b1f11
-- 
2.50.0