In the Linux kernel, the following vulnerability has been resolved:
x86/sev: Use TSC_FACTOR for Secure TSC frequency calculation
When using Secure TSC, the GUEST_TSC_FREQ MSR reports a frequency based on the nominal P0 frequency, which deviates slightly (typically ~0.2%) from the actual mean TSC frequency due to clocking parameters.
Over extended VM uptime, this discrepancy accumulates, causing clock skew between the hypervisor and a SEV-SNP VM, leading to early timer interrupts as perceived by the guest.
The guest kernel relies on the reported nominal frequency for TSC-based timekeeping, while the actual frequency set during SNP_LAUNCH_START may differ. This mismatch results in inaccurate time calculations, causing the guest to perceive hrtimers as firing earlier than expected.
Utilize the TSC_FACTOR from the SEV firmware's secrets page (see "Secrets Page Format" in the SNP Firmware ABI Specification) to calculate the mean TSC frequency, ensuring accurate timekeeping and mitigating clock skew in SEV-SNP VMs.
Use early_ioremap_encrypted() to map the secrets page as ioremap_encrypted() uses kmalloc() which is not available during early TSC initialization and causes a panic.
[ bp: Drop the silly dummy var: https://lore.kernel.org/r/20250630192726.GBaGLlHl84xIopx4Pt@fat_crate.local ]
CVSS Details
- CVSS 3.1 Base Score: 7.3
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Suse | — | Upgrade dtb-lgUpgrade kernel-default-optionalUpgrade kernel-64kb-optionalUpgrade kernel-source-vanillaUpgrade kernel-rt-extraUpgrade kernel-default-develUpgrade dtb-amazonUpgrade kernel-rt-optionalUpgrade ocfs2-kmp-64kbUpgrade dlm-kmp-64kbUpgrade kernel-64kbUpgrade kernel-rt-livepatchUpgrade dtb-broadcomUpgrade dtb-sprdUpgrade kernel-sourceUpgrade dtb-freescaleUpgrade dtb-hisiliconUpgrade dtb-qcomUpgrade cluster-md-kmp-64kbUpgrade kernel-kvmsmall-develUpgrade dtb-alteraUpgrade kernel-default-vdsoUpgrade kernel-develUpgrade dtb-caviumUpgrade kernel-64kb-extraUpgrade kernel-obs-buildUpgrade kselftests-kmp-64kbUpgrade ocfs2-kmp-defaultUpgrade dtb-xilinxUpgrade kernel-64kb-develUpgrade dtb-exynosUpgrade gfs2-kmp-defaultUpgrade kernel-rt-develUpgrade dtb-allwinnerUpgrade kernel-default-livepatchUpgrade cluster-md-kmp-rtUpgrade kernel-rtUpgrade kernel-obs-qaUpgrade kselftests-kmp-rtUpgrade dtb-amdUpgrade dtb-marvellUpgrade dtb-armUpgrade kernel-defaultUpgrade dtb-amlogicUpgrade kernel-symsUpgrade kernel-kvmsmall-vdsoUpgrade dtb-socionextUpgrade cluster-md-kmp-defaultUpgrade dtb-mediatekUpgrade dtb-appleUpgrade kernel-docs-htmlUpgrade dlm-kmp-rtUpgrade kernel-rt-livepatch-develUpgrade kernel-kvmsmallUpgrade dtb-nvidiaUpgrade dtb-apmUpgrade dlm-kmp-defaultUpgrade kernel-docsUpgrade kernel-default-livepatch-develUpgrade kernel-default-extraUpgrade dtb-rockchipUpgrade gfs2-kmp-rtUpgrade dtb-renesasUpgrade kernel-rt-vdsoUpgrade gfs2-kmp-64kbUpgrade ocfs2-kmp-rtUpgrade kernel-zfcpdumpUpgrade kernel-macrosUpgrade kselftests-kmp-default | Dec 5, 2025 | Nov 6, 2025 |
| Ubuntu | — | Upgrade linux-image-6.14.0-1020-gcp-64kUpgrade linux-image-generic-64kUpgrade linux-image-aws-64k-6.14Upgrade linux-image-oracleUpgrade linux-image-genericUpgrade linux-image-virtual-6.14Upgrade linux-image-aws-64kUpgrade linux-image-6.14.0-1017-awsUpgrade linux-image-oem-24.04aUpgrade linux-image-oem-6.14Upgrade linux-image-oem-24.04Upgrade linux-image-gcpUpgrade linux-image-6.14.0-1017-aws-64kUpgrade linux-image-generic-64k-6.14Upgrade linux-image-generic-hwe-24.04Upgrade linux-image-oracle-64kUpgrade linux-image-virtualUpgrade linux-image-realtimeUpgrade linux-image-virtual-hwe-24.04Upgrade linux-image-6.14.0-1016-realtimeUpgrade linux-image-azure-6.14Upgrade linux-image-realtime-hwe-24.04Upgrade linux-image-realtime-6.14Upgrade linux-image-oracle-64k-6.14Upgrade linux-image-6.14.0-1018-raspiUpgrade linux-image-raspiUpgrade linux-image-6.14.0-1020-gcpUpgrade linux-image-6.14.0-1017-azureUpgrade linux-image-azureUpgrade linux-image-gcp-6.14Upgrade linux-image-raspi-6.14Upgrade linux-image-6.14.0-1017-oracle-64kUpgrade linux-image-6.14.0-1016-oemUpgrade linux-image-6.14.0-36-generic-64kUpgrade linux-image-gcp-64k-6.14Upgrade linux-image-generic-6.14Upgrade linux-image-6.14.0-1017-oracleUpgrade linux-image-gcp-64kUpgrade linux-image-aws-6.14Upgrade linux-image-generic-64k-hwe-24.04Upgrade linux-image-awsUpgrade linux-image-6.14.0-36-genericUpgrade linux-image-oracle-6.14 | Nov 25, 2025 | Nov 21, 2025 |
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