Academic Journal
Cache Coherency and NUMA Balancing Performance Pathologies in AMD SEV-SNP Confidential Virtual Machines: A Real-World Kernel-Level Case Study.
| Τίτλος: | Cache Coherency and NUMA Balancing Performance Pathologies in AMD SEV-SNP Confidential Virtual Machines: A Real-World Kernel-Level Case Study. |
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| Συγγραφείς: | Kalra, Ashish |
| Πηγή: | Journal of Computational Analysis & Applications. 2026, Vol. 35 Issue 5, p245-256. 12p. |
| Θεματικοί όροι: | *Computer memory management, *Virtual machine systems, *Computer architecture, *Data encryption, *Kernel operating systems |
| Περίληψη: | AMD Secure Nested Paging (SNP) provides hardware-enforced memory encryption for confidential virtual machines (VMs), but its security mechanisms can interact unexpectedly with the Linux kernel's memory management subsystems. This article presents a kernel-level case study of a performance regression in SNP guests caused by a security fix for cache incoherency in AMD Secure Encrypted Virtualization (SEV). The fix invoked system-wide cache flushes via wbinvd_on_all_cpus() through MMU invalidation notifiers, which triggered a pathological interaction with the NUMA autobalancing subsystem on large hosts. On a 500-CPU test system, SNP guests with 128 virtual CPUs and ≥10 GB of memory exhibited kernel soft lockups and Read-Copy-Update (RCU) stalls. These were traced to spurious MMU notifier events fired by the NUMA autobalancer on pinned, non-migratable guest memory pages. This article identifies the root cause through kernel stack trace forensics, evaluates upstream remediation alternatives, and examines the definitive fix: removing host virtual address mappings for private encrypted guest memory via the guest_memfd abstraction. The findings highlight the importance of co-designing security mitigations with performance-critical kernel subsystems. [ABSTRACT FROM AUTHOR] |
| Βάση Δεδομένων: | Academic Search Index |
| FullText | Text: Availability: 0 |
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| Header | DbId: asx DbLabel: Academic Search Index An: 194406251 RelevancyScore: 1431 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 1430.76245117188 |
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| Items | – Name: Title Label: Title Group: Ti Data: Cache Coherency and NUMA Balancing Performance Pathologies in AMD SEV-SNP Confidential Virtual Machines: A Real-World Kernel-Level Case Study. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Kalra%2C+Ashish%22">Kalra, Ashish</searchLink> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Computational+Analysis+%26+Applications%22">Journal of Computational Analysis & Applications</searchLink>. 2026, Vol. 35 Issue 5, p245-256. 12p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Computer+memory+management%22">Computer memory management</searchLink><br />*<searchLink fieldCode="DE" term="%22Virtual+machine+systems%22">Virtual machine systems</searchLink><br />*<searchLink fieldCode="DE" term="%22Computer+architecture%22">Computer architecture</searchLink><br />*<searchLink fieldCode="DE" term="%22Data+encryption%22">Data encryption</searchLink><br />*<searchLink fieldCode="DE" term="%22Kernel+operating+systems%22">Kernel operating systems</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: AMD Secure Nested Paging (SNP) provides hardware-enforced memory encryption for confidential virtual machines (VMs), but its security mechanisms can interact unexpectedly with the Linux kernel's memory management subsystems. This article presents a kernel-level case study of a performance regression in SNP guests caused by a security fix for cache incoherency in AMD Secure Encrypted Virtualization (SEV). The fix invoked system-wide cache flushes via wbinvd_on_all_cpus() through MMU invalidation notifiers, which triggered a pathological interaction with the NUMA autobalancing subsystem on large hosts. On a 500-CPU test system, SNP guests with 128 virtual CPUs and ≥10 GB of memory exhibited kernel soft lockups and Read-Copy-Update (RCU) stalls. These were traced to spurious MMU notifier events fired by the NUMA autobalancer on pinned, non-migratable guest memory pages. This article identifies the root cause through kernel stack trace forensics, evaluates upstream remediation alternatives, and examines the definitive fix: removing host virtual address mappings for private encrypted guest memory via the guest_memfd abstraction. The findings highlight the importance of co-designing security mitigations with performance-critical kernel subsystems. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.48047/jocaaa.2026.35.05.15 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 245 Subjects: – SubjectFull: Computer memory management Type: general – SubjectFull: Virtual machine systems Type: general – SubjectFull: Computer architecture Type: general – SubjectFull: Data encryption Type: general – SubjectFull: Kernel operating systems Type: general Titles: – TitleFull: Cache Coherency and NUMA Balancing Performance Pathologies in AMD SEV-SNP Confidential Virtual Machines: A Real-World Kernel-Level Case Study. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Kalra, Ashish IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: 2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 15211398 Numbering: – Type: volume Value: 35 – Type: issue Value: 5 Titles: – TitleFull: Journal of Computational Analysis & Applications Type: main |
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