[PATCH 3.2 1/4] kvm: nVMX: Allow L1 to intercept software exceptions (#BP and #OF)

[Ben Hutchings]

3.2.86-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jim Mattson <jmatt...@google.com>

commit ef85b67385436ddc1998f45f1d6a210f935b3388 upstream.

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 <jmatt...@google.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 arch/x86/kvm/vmx.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -876,10 +876,10 @@ static inline bool nested_cpu_has_virtua
        return vmcs12->pin_based_vm_exec_control & PIN_BASED_VIRTUAL_NMIS;
 }
 
-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);
@@ -4225,7 +4225,7 @@ static int handle_exception(struct kvm_v
                return 0;
        }
 
-       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)) {
@@ -5773,7 +5773,7 @@ static bool nested_vmx_exit_handled(stru
 
        switch (exit_reason) {
        case EXIT_REASON_EXCEPTION_NMI:
-               if (!is_exception(intr_info))
+               if (is_nmi(intr_info))
                        return 0;
                else if (is_page_fault(intr_info))
                        return enable_ept;
@@ -5973,8 +5973,7 @@ static void vmx_complete_atomic_exit(str
                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);