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[192.75.244.14]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ad80219f83sm2355155a91.6.2026.10.20.21.26.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 21:26:07 -0700 (PDT) From: ma.mandourr@gmail.com To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Mahmoud Abumandour Subject: [PATCH 0/2] KVM: nVMX: Don't clobber VM-Entry instruction length on soft INTn exits Date: Tue, 20 Oct 2026 21:26:01 -0700 Message-ID: <20261021042603.608292-1-ma.mandourr@gmail.com> X-Mailer: git-send-email 2.43.0 X-Mailing-List: kvm@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Mahmoud Abumandour KVM writes the length of a soft INTn that L2 was vectoring at the time of a nested VM-Exit into vmcs12's VM-Entry instruction length, an L1-owned control, instead of the VM-Exit instruction length. Patch 1 fixes it and patch 2 adds a selftest. Found with a fuzzer for VMX isolation. The selftest patch was written with the help of an LLM coding assistant (Claude Opus 5.5). kvm-x86/next was run as a nested hypervisor under QEMU. The selftest passes only with patch 1, and other nested VMX selftests are unaffected. Mahmoud Abumandour (2): KVM: nVMX: Don't clobber VM-Entry instruction length when saving soft INTn KVM: selftests: Add test for nested VM-Exits while vectoring soft INTs arch/x86/kvm/vmx/nested.c | 2 +- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../kvm/x86/vmx_soft_int_vectoring_test.c | 105 ++++++++++++++++++ 3 files changed, 107 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/kvm/x86/vmx_soft_int_vectoring_test.c base-commit: dea4f6380f4ec96e8f3b0aaf2343764bd0d25ef4 -- 2.43.0