[PATCH 5.6 002/194] kvm: nVMX: reflect MTF VM-exits if injected by L1

Greg Kroah-Hartman
2020-05-18T18:14:48Z

From: Oliver Upton <oupton@google.com>

[ Upstream commit b045ae906b42afb361dc7ecf1a3cea110fb0a65f ]

According to SDM 26.6.2, it is possible to inject an MTF VM-exit via the
VM-entry interruption-information field regardless of the 'monitor trap
flag' VM-execution control. KVM appropriately copies the VM-entry
interruption-information field from vmcs12 to vmcs02. However, if L1
has not set the 'monitor trap flag' VM-execution control, KVM fails to
reflect the subsequent MTF VM-exit into L1.

Fix this by consulting the VM-entry interruption-information field of
vmcs12 to determine if L1 has injected the MTF VM-exit. If so, reflect
the exit, regardless of the 'monitor trap flag' VM-execution control.

Fixes: 5f3d45e7f282 ("kvm/x86: add support for MONITOR_TRAP_FLAG")
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200414224746.240324-1-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/vmx/nested.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b773989308015..3a2f05ef51fa4 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5504,6 +5504,23 @@ static bool nested_vmx_exit_handled_vmcs_access(struct kvm_vcpu *vcpu,
return 1 & (b >> (field & 7));
}

+static bool nested_vmx_exit_handled_mtf(struct vmcs12 *vmcs12)
+{
+ u32 entry_intr_info = vmcs12->vm_entry_intr_info_field;
+
+ if (nested_cpu_has_mtf(vmcs12))
+ return true;
+
+ /*
+ * An MTF VM-exit may be injected into the guest by setting the
+ * interruption-type to 7 (other event) and the vector field to 0. Such
+ * is the case regardless of the 'monitor trap flag' VM-execution
+ * control.
+ */
+ return entry_intr_info == (INTR_INFO_VALID_MASK
+ | INTR_TYPE_OTHER_EVENT);
+}
+
/*
* Return 1 if we should exit from L2 to L1 to handle an exit, or 0 if we
* should handle it ourselves in L0 (and then continue L2). Only call this
@@ -5618,7 +5635,7 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
case EXIT_REASON_MWAIT_INSTRUCTION:
return nested_cpu_has(vmcs12, CPU_BASED_MWAIT_EXITING);
case EXIT_REASON_MONITOR_TRAP_FLAG:
- return nested_cpu_has_mtf(vmcs12);
+ return nested_vmx_exit_handled_mtf(vmcs12);
case EXIT_REASON_MONITOR_INSTRUCTION:
return nested_cpu_has(vmcs12, CPU_BASED_MONITOR_EXITING);
case EXIT_REASON_PAUSE_INSTRUCTION:
--
2.20.1