KVM: SVM: Preserve TLB control (i.e. pending TLB flush) on failed VMRUN
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Preserve TLB control (i.e. pending TLB flush) on failed VMRUN Don't reset the VMCB's TLB control back to "do nothing" on a failed VMRUN, as empirical testing shows that the CPU performs the requested TLB flush if and only if VMRUN is successful, i.e. clearing TLB control on a failed VMRUN effectively drops a TLB flush. Explicitly track the need to flush all ASIDs on a per-CPU basis, as the ASID reuse condition is tied to the pCPU, not to the vCPU. As a bonus, this also obviates the need to avoid clobbering FLUSH_ALL_ASID with TLB_CONTROL_FLUSH_ASID, e.g. in svm_flush_tlb_asid(). Deliberately don't bother saving/restoring the "old" tlb_ctl on failure, in quotes because it's not exactly the old tlb_ctl, it's the tlb_ctl from after pre_svm_run(), but before updating tlb_ctl for flush_all_asids. If VMRUN fails and TLB_CONTROL_FLUSH_ALL_ASID is forced, then the next successful run of the VMCB *may* unnecessarily flush all ASIDs, which strictly speaking could result in noisy neighbor issues. However, the fact that new_asid() is already guest-triggerable, because of KVM's flawed behavior of clearing the ASID on emulated INIT, means that a guest can already trigger a flush of all ASIDs at roughly the same rate. And once KVM stops clobbering the ASID on emulated INIT, *or* assigns a static ASID to each vCPU, this flaw goes away.
CVE-2026-98715
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98715
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "38e5e92fe8c02a8766459d505423b855caf9af1f",
"lessThan": "fd873c3d1b5240e80365f09e758e8c96b88a7cdb",
"versionType": "git"
},
{
"status": "affected",
"version": "38e5e92fe8c02a8766459d505423b855caf9af1f",
"lessThan": "60d93c27859fb3ec5b5a689e24de303f166477d0",
"versionType": "git"
}
],
"programFiles": [
"arch/x86/kvm/svm/svm.c",
"arch/x86/kvm/svm/svm.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.38"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.38",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/x86/kvm/svm/svm.c",
"arch/x86/kvm/svm/svm.h"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98715
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38697 · Revision 1
- Added to Heist Feed
- Publisher date