[Devel] [PATCH RHEL7 COMMIT] ms/kvm: nVMX: Allow L1 to intercept software exceptions (#BP and #OF)

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-514.vz7.27.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.vz7.27.9
------>
commit 7efd73d3548321581182145c349fadcce13ad00b
Author: Jim Mattson <jmattson at google.com>
Date:   Wed Jan 11 18:56:16 2017 +0400

    ms/kvm: nVMX: Allow L1 to intercept software exceptions (#BP and #OF)
    
    When L2 exits to L0 due to "exception or NMI", software exceptions
    (#BP and #OF) for which L1 has requested an intercept should be
    handled by L1 rather than L0. Previously, only hardware exceptions
    were forwarded to L1.
    
    Signed-off-by: Jim Mattson <jmattson at google.com>
    Cc: stable at vger.kernel.org
    Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
    
    Backport of ms commit ef85b67385436ddc1998f45f1d6a210f935b3388
    Fixes CVE-2016-9588
    https://vulners.com/cve/CVE-2016-9588
    
    https://jira.sw.ru/browse/PSBM-58194
    
    Signed-off-by: Evgeny Yakovlev <eyakovlev at virtuozzo.com>
---
 arch/x86/kvm/vmx.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3d39923..8dea43b9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1243,10 +1243,10 @@ static inline bool nested_cpu_has_posted_intr(struct vmcs12 *vmcs12)
 	return vmcs12->pin_based_vm_exec_control & PIN_BASED_POSTED_INTR;
 }
 
-static inline bool is_exception(u32 intr_info)
+static inline bool is_nmi(u32 intr_info)
 {
 	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
-		== (INTR_TYPE_HARD_EXCEPTION | INTR_INFO_VALID_MASK);
+		== (INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK);
 }
 
 static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
@@ -5185,7 +5185,7 @@ static int handle_exception(struct kvm_vcpu *vcpu)
 	if (is_machine_check(intr_info))
 		return handle_machine_check(vcpu);
 
-	if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == INTR_TYPE_NMI_INTR)
+	if (is_nmi(intr_info))
 		return 1;  /* already handled by vmx_vcpu_run() */
 
 	if (is_no_device(intr_info)) {
@@ -7629,7 +7629,7 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
 
 	switch (exit_reason) {
 	case EXIT_REASON_EXCEPTION_NMI:
-		if (!is_exception(intr_info))
+		if (is_nmi(intr_info))
 			return false;
 		else if (is_page_fault(intr_info))
 			return enable_ept;
@@ -8226,8 +8226,7 @@ static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx)
 		kvm_machine_check();
 
 	/* We need to handle NMIs before interrupts are enabled */
-	if ((exit_intr_info & INTR_INFO_INTR_TYPE_MASK) == INTR_TYPE_NMI_INTR &&
-	    (exit_intr_info & INTR_INFO_VALID_MASK)) {
+	if (is_nmi(exit_intr_info)) {
 		kvm_before_handle_nmi(&vmx->vcpu);
 		asm("int $2");
 		kvm_after_handle_nmi(&vmx->vcpu);