In the Linux kernel, the following vulnerability has been resolved:
KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped
Wire up a gmem_invalidate_range() call for SNP VMs, and use it to force
vCPUs to reload/recheck their guest-provided VMSA if the backing gmem
page is being invalidated, e.g. is being PUNCH_HOLE'd. Use the same core
logic to handle invalidations as VMX does for the APIC-access page, as the
two concepts are nearly identical: shove the physical address of a page
into the vCPU's control structure:
1. Snapshot the invalidation sequence counter
2. Grab the pfn (from guest_memfd in this case)
3. Acquire mmu_lock for read
4. Re-request reload if retry is needed, otherwise commit the change.
Note, the re-request action in #4 is necessary as KVM's retry logic is
fuzzy, i.e. can get false positives. If the guest_memfd page has been
dropped, at some point a subsequent reload will fail to get a PFN from
guest_memfd, and KVM will fail KVM_RUN. If the retry was due to a false
positive, KVM will retry until there are no relevant MMU notifier events
(and will retry in the "outer" loop, i.e. will drop locks and resched as
needed).
Note #2! Take care to invalidate the VMSA when a relevant memslot is
DELETED or MOVED, as invalidations in response to PUNCH_HOLE are predicated
on memslot bindings (KVM doesn't know what GFN range(s) to invalidate
without a binding). And more importantly, the VMSA mapping requires a
memslot, i.e. must be invalidated if its memslots disappears, regardless of
the state of the underlying guest_memfd inode.
Failure to invalidate the vCPU's control.vmsa_pa (which is checked by
pre_sev_run()) can prevent KVM from properly freeing the page as firmware
will reject the RMPUPDATE to reclaim the page with FAIL_INUSE if the vCPU
is actively running, i.e. if VMSA page is in-use. That in turn leads to an
RMP #PF on the next use, as the page will still be assigned to the SNP VM.
SEV-SNP: RMPUPDATE failed for PFN 78d198, pg_level: 1, ret: 3
SEV-SNP: PFN 0x78d198, RMP entry: [0xfff0000000144001 - 0x000000000000000f]
CPU: 3 UID: 0 PID: 31345 Comm: sev_snp_vmsa_pu Tainted: G U O
Tainted: [U]=USER, [O]=OOT_MODULE
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026
Call Trace:
<TASK>
dump_stack_lvl+0x54/0x70
rmpupdate+0x12c/0x140
rmp_make_shared+0x3b/0x60
sev_gmem_invalidate+0xe0/0x170 [kvm_amd]
delete_from_page_cache_batch+0x1d8/0x220
truncate_inode_pages_range+0x120/0x3d0
kvm_gmem_fallocate+0x19a/0x270 [kvm]
vfs_fallocate+0x1bc/0x1f0
__x64_sys_fallocate+0x48/0x70
do_syscall_64+0x10a/0x480
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x496c7e
</TASK>
------------[ cut here ]------------
SEV: Failed to update RMP entry for PFN 0x78d198 error -14
WARNING: arch/x86/kvm/svm/sev.c:5160 at sev_gmem_invalidate+0x126/0x170 [kvm_amd], CPU#3: sev_snp_vmsa_pu/31345
CPU: 3 UID: 0 PID: 31345 Comm: sev_snp_vmsa_pu Tainted: G U O
Tainted: [U]=USER, [O]=OOT_MODULE
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026
RIP: 0010:sev_gmem_invalidate+0x12b/0x170 [kvm_amd]
Call Trace:
<TASK>
delete_from_page_cache_batch+0x1d8/0x220
truncate_inode_pages_range+0x120/0x3d0
kvm_gmem_fallocate+0x19a/0x270 [kvm]
vfs_fallocate+0x1bc/0x1f0
__x64_sys_fallocate+0x48/0x70
do_syscall_64+0x10a/0x480
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x496c7e
</TASK>
irq event stamp: 20689
hardirqs last enabled at (20699): [<ffffffff8e76092c>] __console_unlock+0x5c/0x60
hardirqs last disabled at (20708): [<ffffffff8e760911>] __console_unlock+0x41/0x60
softirqs last enabled at (20722): [<ffffffff8e6cd74e>] __irq_exit_rcu+0x7e/0x140
softirqs last disabled at (20717): [<ffffffff8e6cd74e>] __irq_exit_rcu+0x7e/0x140
---[ end trace 0000000000000000 ]---
BUG: unable to handle page fault for address: ffff99
---truncated---
KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped
Wire up a gmem_invalidate_range() call for SNP VMs, and use it to force
vCPUs to reload/recheck their guest-provided VMSA if the backing gmem
page is being invalidated, e.g. is being PUNCH_HOLE'd. Use the same core
logic to handle invalidations as VMX does for the APIC-access page, as the
two concepts are nearly identical: shove the physical address of a page
into the vCPU's control structure:
1. Snapshot the invalidation sequence counter
2. Grab the pfn (from guest_memfd in this case)
3. Acquire mmu_lock for read
4. Re-request reload if retry is needed, otherwise commit the change.
Note, the re-request action in #4 is necessary as KVM's retry logic is
fuzzy, i.e. can get false positives. If the guest_memfd page has been
dropped, at some point a subsequent reload will fail to get a PFN from
guest_memfd, and KVM will fail KVM_RUN. If the retry was due to a false
positive, KVM will retry until there are no relevant MMU notifier events
(and will retry in the "outer" loop, i.e. will drop locks and resched as
needed).
Note #2! Take care to invalidate the VMSA when a relevant memslot is
DELETED or MOVED, as invalidations in response to PUNCH_HOLE are predicated
on memslot bindings (KVM doesn't know what GFN range(s) to invalidate
without a binding). And more importantly, the VMSA mapping requires a
memslot, i.e. must be invalidated if its memslots disappears, regardless of
the state of the underlying guest_memfd inode.
Failure to invalidate the vCPU's control.vmsa_pa (which is checked by
pre_sev_run()) can prevent KVM from properly freeing the page as firmware
will reject the RMPUPDATE to reclaim the page with FAIL_INUSE if the vCPU
is actively running, i.e. if VMSA page is in-use. That in turn leads to an
RMP #PF on the next use, as the page will still be assigned to the SNP VM.
SEV-SNP: RMPUPDATE failed for PFN 78d198, pg_level: 1, ret: 3
SEV-SNP: PFN 0x78d198, RMP entry: [0xfff0000000144001 - 0x000000000000000f]
CPU: 3 UID: 0 PID: 31345 Comm: sev_snp_vmsa_pu Tainted: G U O
Tainted: [U]=USER, [O]=OOT_MODULE
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026
Call Trace:
<TASK>
dump_stack_lvl+0x54/0x70
rmpupdate+0x12c/0x140
rmp_make_shared+0x3b/0x60
sev_gmem_invalidate+0xe0/0x170 [kvm_amd]
delete_from_page_cache_batch+0x1d8/0x220
truncate_inode_pages_range+0x120/0x3d0
kvm_gmem_fallocate+0x19a/0x270 [kvm]
vfs_fallocate+0x1bc/0x1f0
__x64_sys_fallocate+0x48/0x70
do_syscall_64+0x10a/0x480
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x496c7e
</TASK>
------------[ cut here ]------------
SEV: Failed to update RMP entry for PFN 0x78d198 error -14
WARNING: arch/x86/kvm/svm/sev.c:5160 at sev_gmem_invalidate+0x126/0x170 [kvm_amd], CPU#3: sev_snp_vmsa_pu/31345
CPU: 3 UID: 0 PID: 31345 Comm: sev_snp_vmsa_pu Tainted: G U O
Tainted: [U]=USER, [O]=OOT_MODULE
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026
RIP: 0010:sev_gmem_invalidate+0x12b/0x170 [kvm_amd]
Call Trace:
<TASK>
delete_from_page_cache_batch+0x1d8/0x220
truncate_inode_pages_range+0x120/0x3d0
kvm_gmem_fallocate+0x19a/0x270 [kvm]
vfs_fallocate+0x1bc/0x1f0
__x64_sys_fallocate+0x48/0x70
do_syscall_64+0x10a/0x480
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x496c7e
</TASK>
irq event stamp: 20689
hardirqs last enabled at (20699): [<ffffffff8e76092c>] __console_unlock+0x5c/0x60
hardirqs last disabled at (20708): [<ffffffff8e760911>] __console_unlock+0x41/0x60
softirqs last enabled at (20722): [<ffffffff8e6cd74e>] __irq_exit_rcu+0x7e/0x140
softirqs last disabled at (20717): [<ffffffff8e6cd74e>] __irq_exit_rcu+0x7e/0x140
---[ end trace 0000000000000000 ]---
BUG: unable to handle page fault for address: ffff99
---truncated---
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 16 Sep 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped Wire up a gmem_invalidate_range() call for SNP VMs, and use it to force vCPUs to reload/recheck their guest-provided VMSA if the backing gmem page is being invalidated, e.g. is being PUNCH_HOLE'd. Use the same core logic to handle invalidations as VMX does for the APIC-access page, as the two concepts are nearly identical: shove the physical address of a page into the vCPU's control structure: 1. Snapshot the invalidation sequence counter 2. Grab the pfn (from guest_memfd in this case) 3. Acquire mmu_lock for read 4. Re-request reload if retry is needed, otherwise commit the change. Note, the re-request action in #4 is necessary as KVM's retry logic is fuzzy, i.e. can get false positives. If the guest_memfd page has been dropped, at some point a subsequent reload will fail to get a PFN from guest_memfd, and KVM will fail KVM_RUN. If the retry was due to a false positive, KVM will retry until there are no relevant MMU notifier events (and will retry in the "outer" loop, i.e. will drop locks and resched as needed). Note #2! Take care to invalidate the VMSA when a relevant memslot is DELETED or MOVED, as invalidations in response to PUNCH_HOLE are predicated on memslot bindings (KVM doesn't know what GFN range(s) to invalidate without a binding). And more importantly, the VMSA mapping requires a memslot, i.e. must be invalidated if its memslots disappears, regardless of the state of the underlying guest_memfd inode. Failure to invalidate the vCPU's control.vmsa_pa (which is checked by pre_sev_run()) can prevent KVM from properly freeing the page as firmware will reject the RMPUPDATE to reclaim the page with FAIL_INUSE if the vCPU is actively running, i.e. if VMSA page is in-use. That in turn leads to an RMP #PF on the next use, as the page will still be assigned to the SNP VM. SEV-SNP: RMPUPDATE failed for PFN 78d198, pg_level: 1, ret: 3 SEV-SNP: PFN 0x78d198, RMP entry: [0xfff0000000144001 - 0x000000000000000f] CPU: 3 UID: 0 PID: 31345 Comm: sev_snp_vmsa_pu Tainted: G U O Tainted: [U]=USER, [O]=OOT_MODULE Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026 Call Trace: <TASK> dump_stack_lvl+0x54/0x70 rmpupdate+0x12c/0x140 rmp_make_shared+0x3b/0x60 sev_gmem_invalidate+0xe0/0x170 [kvm_amd] delete_from_page_cache_batch+0x1d8/0x220 truncate_inode_pages_range+0x120/0x3d0 kvm_gmem_fallocate+0x19a/0x270 [kvm] vfs_fallocate+0x1bc/0x1f0 __x64_sys_fallocate+0x48/0x70 do_syscall_64+0x10a/0x480 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x496c7e </TASK> ------------[ cut here ]------------ SEV: Failed to update RMP entry for PFN 0x78d198 error -14 WARNING: arch/x86/kvm/svm/sev.c:5160 at sev_gmem_invalidate+0x126/0x170 [kvm_amd], CPU#3: sev_snp_vmsa_pu/31345 CPU: 3 UID: 0 PID: 31345 Comm: sev_snp_vmsa_pu Tainted: G U O Tainted: [U]=USER, [O]=OOT_MODULE Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026 RIP: 0010:sev_gmem_invalidate+0x12b/0x170 [kvm_amd] Call Trace: <TASK> delete_from_page_cache_batch+0x1d8/0x220 truncate_inode_pages_range+0x120/0x3d0 kvm_gmem_fallocate+0x19a/0x270 [kvm] vfs_fallocate+0x1bc/0x1f0 __x64_sys_fallocate+0x48/0x70 do_syscall_64+0x10a/0x480 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x496c7e </TASK> irq event stamp: 20689 hardirqs last enabled at (20699): [<ffffffff8e76092c>] __console_unlock+0x5c/0x60 hardirqs last disabled at (20708): [<ffffffff8e760911>] __console_unlock+0x41/0x60 softirqs last enabled at (20722): [<ffffffff8e6cd74e>] __irq_exit_rcu+0x7e/0x140 softirqs last disabled at (20717): [<ffffffff8e6cd74e>] __irq_exit_rcu+0x7e/0x140 ---[ end trace 0000000000000000 ]--- BUG: unable to handle page fault for address: ffff99 ---truncated--- | |
| Title | KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-16T10:33:38.790Z
Reserved: 2026-09-11T19:38:34.783Z
Link: CVE-2026-90040
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-16T11:17:17.213
Modified: 2026-09-16T11:17:17.213
Link: CVE-2026-90040
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.