| From c9bcd3e3335d0a29d89fabd2c385e1b989e6f1b0 Mon Sep 17 00:00:00 2001 |
| From: "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@amd.com> |
| Date: Tue, 14 May 2019 15:49:52 +0000 |
| Subject: kvm: svm/avic: fix off-by-one in checking host APIC ID |
| |
| From: Suthikulpanit, Suravee <Suravee.Suthikulpanit@amd.com> |
| |
| commit c9bcd3e3335d0a29d89fabd2c385e1b989e6f1b0 upstream. |
| |
| Current logic does not allow VCPU to be loaded onto CPU with |
| APIC ID 255. This should be allowed since the host physical APIC ID |
| field in the AVIC Physical APIC table entry is an 8-bit value, |
| and APIC ID 255 is valid in system with x2APIC enabled. |
| Instead, do not allow VCPU load if the host APIC ID cannot be |
| represented by an 8-bit value. |
| |
| Also, use the more appropriate AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK |
| instead of AVIC_MAX_PHYSICAL_ID_COUNT. |
| |
| Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/kvm/svm.c | 6 +++++- |
| 1 file changed, 5 insertions(+), 1 deletion(-) |
| |
| --- a/arch/x86/kvm/svm.c |
| +++ b/arch/x86/kvm/svm.c |
| @@ -2024,7 +2024,11 @@ static void avic_vcpu_load(struct kvm_vc |
| if (!kvm_vcpu_apicv_active(vcpu)) |
| return; |
| |
| - if (WARN_ON(h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT)) |
| + /* |
| + * Since the host physical APIC id is 8 bits, |
| + * we can support host APIC ID upto 255. |
| + */ |
| + if (WARN_ON(h_physical_id > AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK)) |
| return; |
| |
| entry = READ_ONCE(*(svm->avic_physical_id_cache)); |
