From: Sean Christopherson seanjc@google.com
commit 6c6ab524cfae0799e55c82b2c1d61f1af0156f8d upstream.
Treat the NX bit as valid when using NPT, as KVM will set the NX bit when the NX huge page mitigation is enabled (mindblowing) and trigger the WARN that fires on reserved SPTE bits being set.
KVM has required NX support for SVM since commit b26a71a1a5b9 ("KVM: SVM: Refuse to load kvm_amd if NX support is not available") for exactly this reason, but apparently it never occurred to anyone to actually test NPT with the mitigation enabled.
------------[ cut here ]------------ spte = 0x800000018a600ee7, level = 2, rsvd bits = 0x800f0000001fe000 WARNING: CPU: 152 PID: 15966 at arch/x86/kvm/mmu/spte.c:215 make_spte+0x327/0x340 [kvm] Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 10.48.0 01/27/2022 RIP: 0010:make_spte+0x327/0x340 [kvm] Call Trace: <TASK> tdp_mmu_map_handle_target_level+0xc3/0x230 [kvm] kvm_tdp_mmu_map+0x343/0x3b0 [kvm] direct_page_fault+0x1ae/0x2a0 [kvm] kvm_tdp_page_fault+0x7d/0x90 [kvm] kvm_mmu_page_fault+0xfb/0x2e0 [kvm] npf_interception+0x55/0x90 [kvm_amd] svm_invoke_exit_handler+0x31/0xf0 [kvm_amd] svm_handle_exit+0xf6/0x1d0 [kvm_amd] vcpu_enter_guest+0xb6d/0xee0 [kvm] ? kvm_pmu_trigger_event+0x6d/0x230 [kvm] vcpu_run+0x65/0x2c0 [kvm] kvm_arch_vcpu_ioctl_run+0x355/0x610 [kvm] kvm_vcpu_ioctl+0x551/0x610 [kvm] __se_sys_ioctl+0x77/0xc0 __x64_sys_ioctl+0x1d/0x20 do_syscall_64+0x44/0xa0 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> ---[ end trace 0000000000000000 ]---
Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20220723013029.1753623-1-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/mmu/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4567,7 +4567,7 @@ reset_tdp_shadow_zero_bits_mask(struct k
if (boot_cpu_is_amd()) __reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(), - context->root_role.level, false, + context->root_role.level, true, boot_cpu_has(X86_FEATURE_GBPAGES), false, true); else