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

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Message-ID: <cover.1752038725.git.kai.huang@intel.com>
Date: Wed,  9 Jul 2025 17:37:58 +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,
	linux-kernel@...r.kernel.org
Subject: [PATCH 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.

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.

Currently only TDX guests are TSC protected.  The SEV-SNP Secure TSC
support will enable protected TSC too and can also benefit from this
series.

[1]: https://lore.kernel.org/kvm/aG0uUdY6QPnit6my@google.com/
[2]: https://lore.kernel.org/kvm/aG2k2BFBJHL-szZc@google.com/

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

 arch/x86/kvm/x86.c | 8 ++++++++
 1 file changed, 8 insertions(+)


base-commit: 6c7ecd725e503bf2ca69ff52c6cc48bb650b1f11
-- 
2.50.0