Re: [PATCH v2 4/7] HV: ignore the NMI injection request for lapic-pt vCPUs


Yan, Like
 

On Mon, Dec 09, 2019 at 04:47:48PM +0000, Kaige Fu wrote:
NMI will be used as notification signal for lapic-pt vCPUs and
ACRN doesn't support vNMI for lapic-pt vCPUs. Because it is not
possible to distinguish between notification NMIs and external NMIs
for lapic-pt vCPUs in some corner cases, eg: we can use a magic number
as identifier of notification NMIs. If it is set when receiving a NMI,
this NMI is processed as notification NMI. Otherwise, it is a external
NMI for lapic-pt vCPUs. It works well most of the time. But it won't work
for some corner cases, eg:

1. The sender CPU sets the identifier.
2. An external NMI occurs on the target CPU and then the target CPU will
treat this NMI as notification NMI by mistake.
3. The sender CPU sends the NMI to target CPU.

So, this patch ignores the pending NMI request and EXCP with vector 2.

Signed-off-by: Kaige Fu <kaige.fu@...>
---
hypervisor/arch/x86/guest/virq.c | 55 ++++++++++++++++++++------------
1 file changed, 35 insertions(+), 20 deletions(-)

diff --git a/hypervisor/arch/x86/guest/virq.c b/hypervisor/arch/x86/guest/virq.c
index a0be3c3d..174c0fb3 100644
--- a/hypervisor/arch/x86/guest/virq.c
+++ b/hypervisor/arch/x86/guest/virq.c
@@ -212,26 +212,36 @@ int32_t vcpu_queue_exception(struct acrn_vcpu *vcpu, uint32_t vector_arg, uint32
static void vcpu_inject_exception(struct acrn_vcpu *vcpu, uint32_t vector)
{
if (bitmap_test_and_clear_lock(ACRN_REQUEST_EXCP, &vcpu->arch.pending_req)) {
-
- if ((exception_type[vector] & EXCEPTION_ERROR_CODE_VALID) != 0U) {
- exec_vmwrite32(VMX_ENTRY_EXCEPTION_ERROR_CODE,
- vcpu->arch.exception_info.error);
- }
+ if (is_lapic_pt_enabled(vcpu) && (vector == IDT_NMI)) {
The restriction is not support vNMI for RTVM, so I think we should use is_lapic_pt_configured() here.

+ /*
+ * NMI will be used as notification signal for lapic-pt vCPUs and we
+ * don't support vNMI yet. So, here we just ignore the NMI injection
+ * request.
+ */
+ pr_warn("Don't allow to inject NMI to lapic-pt vCPU%u. Ignore this request.", vcpu->vcpu_id);
+ vcpu->arch.exception_info.exception = VECTOR_INVALID;
+ } else {
+ if ((exception_type[vector] & EXCEPTION_ERROR_CODE_VALID) != 0U) {
+ exec_vmwrite32(VMX_ENTRY_EXCEPTION_ERROR_CODE,
+ vcpu->arch.exception_info.error);
+ }

- exec_vmwrite32(VMX_ENTRY_INT_INFO_FIELD, VMX_INT_INFO_VALID |
- (exception_type[vector] << 8U) | (vector & 0xFFU));
+ exec_vmwrite32(VMX_ENTRY_INT_INFO_FIELD, VMX_INT_INFO_VALID |
+ (exception_type[vector] << 8U) | (vector & 0xFFU));

- vcpu->arch.exception_info.exception = VECTOR_INVALID;
+ vcpu->arch.exception_info.exception = VECTOR_INVALID;

- /* retain rip for exception injection */
- vcpu_retain_rip(vcpu);
+ /* retain rip for exception injection */
+ vcpu_retain_rip(vcpu);

- /* SDM 17.3.1.1 For any fault-class exception except a debug exception generated in response to an
- * instruction breakpoint, the value pushed for RF is 1.
- * #DB is treated as Trap in get_exception_type, so RF will not be set for instruction breakpoint.
- */
- if (get_exception_type(vector) == EXCEPTION_FAULT) {
- vcpu_set_rflags(vcpu, vcpu_get_rflags(vcpu) | HV_ARCH_VCPU_RFLAGS_RF);
+ /* SDM 17.3.1.1 For any fault-class exception except a debug exception generated
+ * in response to an instruction breakpoint, the value pushed for RF is 1.
+ * #DB is treated as Trap in get_exception_type, so RF will not be set for
+ * instruction breakpoint.
+ */
+ if (get_exception_type(vector) == EXCEPTION_FAULT) {
+ vcpu_set_rflags(vcpu, vcpu_get_rflags(vcpu) | HV_ARCH_VCPU_RFLAGS_RF);
+ }
}
}
}
@@ -389,10 +399,15 @@ int32_t acrn_handle_pending_request(struct acrn_vcpu *vcpu)
if (!injected) {
/* inject NMI before maskable hardware interrupt */
if (bitmap_test_and_clear_lock(ACRN_REQUEST_NMI, pending_req_bits)) {
- /* Inject NMI vector = 2 */
- exec_vmwrite32(VMX_ENTRY_INT_INFO_FIELD,
- VMX_INT_INFO_VALID | (VMX_INT_TYPE_NMI << 8U) | IDT_NMI);
- injected = true;
+ if (!is_lapic_pt_enabled(vcpu)) {
Ditto

+ /* Inject NMI vector = 2 */
+ exec_vmwrite32(VMX_ENTRY_INT_INFO_FIELD,
+ VMX_INT_INFO_VALID | (VMX_INT_TYPE_NMI << 8U) | IDT_NMI);
+ injected = true;
+ } else {
+ pr_warn("Don't allow to inject NMI to lapic-pt vCPU%u. Ignore this request.",
+ vcpu->vcpu_id);
+ }
} else {
/* handling pending vector injection:
* there are many reason inject failed, we need re-inject again
--
2.20.0



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