[PATCH v2 13/25] KVM: VMX: Handle VMX nested exception for FRED
From: Xin Li
Date: Wed Feb 07 2024 - 13:06:28 EST
Set VMX nested exception bit in the VM-entry interruption information
VMCS field when injecting a nested exception using FRED event delivery
to ensure:
1) The nested exception is injected on a correct stack level.
2) The nested bit defined in FRED stack frame is set.
The event stack level used by FRED event delivery depends on whether the
event was a nested exception encountered during delivery of another event,
because a nested exception is "regarded" as happening on ring 0. E.g.,
when #PF is configured to use stack level 1 in IA32_FRED_STKLVLS MSR:
- nested #PF will be delivered on stack level 1 when encountered in
ring 3.
- normal #PF will be delivered on stack level 0 when encountered in
ring 3.
The VMX nested-exception support ensures the correct event stack level is
chosen when a VM entry injects a nested exception.
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
---
Changes since v1:
* Set the nested flag when there is an original interrupt (Chao Gao).
---
arch/x86/include/asm/kvm_host.h | 6 +++--
arch/x86/include/asm/vmx.h | 5 ++--
arch/x86/kvm/svm/svm.c | 4 +--
arch/x86/kvm/vmx/vmx.c | 8 ++++--
arch/x86/kvm/x86.c | 46 ++++++++++++++++++++++++++-------
arch/x86/kvm/x86.h | 1 +
6 files changed, 53 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0d88873eba63..ef278ee0b6ca 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -736,6 +736,7 @@ struct kvm_queued_exception {
u32 error_code;
unsigned long payload;
bool has_payload;
+ bool nested;
};
struct kvm_vcpu_arch {
@@ -2060,8 +2061,9 @@ int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu);
void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload);
-void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
-void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr, bool nested);
+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr,
+ u32 error_code, bool nested);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault);
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 6b796c5c9c2b..68af74e48788 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -134,7 +134,7 @@
#define VMX_BASIC_DUAL_MONITOR_TREATMENT BIT_ULL(49)
#define VMX_BASIC_INOUT BIT_ULL(54)
#define VMX_BASIC_TRUE_CTLS BIT_ULL(55)
-
+#define VMX_BASIC_NESTED_EXCEPTION BIT_ULL(58)
/* VMX_MISC bits and bitmasks */
#define VMX_MISC_INTEL_PT BIT_ULL(14)
@@ -407,8 +407,9 @@ enum vmcs_field {
#define INTR_INFO_INTR_TYPE_MASK 0x700 /* 10:8 */
#define INTR_INFO_DELIVER_CODE_MASK 0x800 /* 11 */
#define INTR_INFO_UNBLOCK_NMI 0x1000 /* 12 */
+#define INTR_INFO_NESTED_EXCEPTION_MASK 0x2000 /* 13 */
#define INTR_INFO_VALID_MASK 0x80000000 /* 31 */
-#define INTR_INFO_RESVD_BITS_MASK 0x7ffff000
+#define INTR_INFO_RESVD_BITS_MASK 0x7fffd000
#define VECTORING_INFO_VECTOR_MASK INTR_INFO_VECTOR_MASK
#define VECTORING_INFO_TYPE_MASK INTR_INFO_INTR_TYPE_MASK
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e90b429c84f1..c220b690a37c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4057,10 +4057,10 @@ static void svm_complete_interrupts(struct kvm_vcpu *vcpu)
if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
u32 err = svm->vmcb->control.exit_int_info_err;
- kvm_requeue_exception_e(vcpu, vector, err);
+ kvm_requeue_exception_e(vcpu, vector, err, false);
} else
- kvm_requeue_exception(vcpu, vector);
+ kvm_requeue_exception(vcpu, vector, false);
break;
case SVM_EXITINTINFO_TYPE_INTR:
kvm_queue_interrupt(vcpu, vector, false);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f622fb90a098..1f265d526daf 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1891,6 +1891,8 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
event_data = to_vmx(vcpu)->fred_xfd_event_data;
vmcs_write64(INJECTED_EVENT_DATA, event_data);
+
+ intr_info |= ex->nested ? INTR_INFO_NESTED_EXCEPTION_MASK : 0;
}
}
@@ -7281,9 +7283,11 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring)
}
if (event_id & INTR_INFO_DELIVER_CODE_MASK)
- kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field));
+ kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field),
+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
else
- kvm_requeue_exception(vcpu, vector);
+ kvm_requeue_exception(vcpu, vector,
+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
break;
case INTR_TYPE_SOFT_INTR:
vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 00c0062726ae..725819262085 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -645,7 +645,8 @@ static void kvm_leave_nested(struct kvm_vcpu *vcpu)
static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
unsigned nr, bool has_error, u32 error_code,
- bool has_payload, unsigned long payload, bool reinject)
+ bool has_payload, unsigned long payload,
+ bool reinject, bool nested)
{
u32 prev_nr;
int class1, class2;
@@ -696,6 +697,13 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.pending = true;
vcpu->arch.exception.injected = false;
}
+
+ vcpu->arch.exception.nested = vcpu->arch.exception.nested ||
+ (kvm_is_fred_enabled(vcpu) &&
+ ((reinject && nested) ||
+ vcpu->arch.nmi_injected ||
+ vcpu->arch.interrupt.injected));
+
vcpu->arch.exception.has_error_code = has_error;
vcpu->arch.exception.vector = nr;
vcpu->arch.exception.error_code = error_code;
@@ -725,8 +733,28 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.injected = false;
vcpu->arch.exception.pending = false;
+ /*
+ * A #DF is NOT a nested event per its definition, however per
+ * FRED spec 5.0 Appendix B, its delivery determines the new
+ * stack level as is done for events occurring when CPL = 0.
+ */
+ vcpu->arch.exception.nested = false;
+
kvm_queue_exception_e(vcpu, DF_VECTOR, 0);
} else {
+ /*
+ * FRED spec 5.0 Appendix B: delivery of a nested exception
+ * determines the new stack level as is done for events
+ * occurring when CPL = 0.
+ *
+ * IOW, FRED event delivery of an event encountered in ring 3
+ * normally uses stack level 0 unconditionally. However, if
+ * the event is an exception nested on any earlier event,
+ * delivery of the nested exception will consult the FRED MSR
+ * IA32_FRED_STKLVLS to determine which stack level to use.
+ */
+ vcpu->arch.exception.nested = kvm_is_fred_enabled(vcpu);
+
/* replace previous exception with a new one in a hope
that instruction re-execution will regenerate lost
exception */
@@ -736,20 +764,20 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr)
{
- kvm_multiple_exception(vcpu, nr, false, 0, false, 0, false);
+ kvm_multiple_exception(vcpu, nr, false, 0, false, 0, false, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception);
-void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr)
+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr, bool nested)
{
- kvm_multiple_exception(vcpu, nr, false, 0, false, 0, true);
+ kvm_multiple_exception(vcpu, nr, false, 0, false, 0, true, nested);
}
EXPORT_SYMBOL_GPL(kvm_requeue_exception);
void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr,
unsigned long payload)
{
- kvm_multiple_exception(vcpu, nr, false, 0, true, payload, false);
+ kvm_multiple_exception(vcpu, nr, false, 0, true, payload, false, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception_p);
@@ -757,7 +785,7 @@ static void kvm_queue_exception_e_p(struct kvm_vcpu *vcpu, unsigned nr,
u32 error_code, unsigned long payload)
{
kvm_multiple_exception(vcpu, nr, true, error_code,
- true, payload, false);
+ true, payload, false, false);
}
int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err)
@@ -829,13 +857,13 @@ void kvm_inject_nmi(struct kvm_vcpu *vcpu)
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
{
- kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, false);
+ kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, false, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception_e);
-void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code, bool nested)
{
- kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, true);
+ kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, true, nested);
}
EXPORT_SYMBOL_GPL(kvm_requeue_exception_e);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 9a52016ebf5a..c1f1d5696080 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -108,6 +108,7 @@ static inline void kvm_clear_exception_queue(struct kvm_vcpu *vcpu)
{
vcpu->arch.exception.pending = false;
vcpu->arch.exception.injected = false;
+ vcpu->arch.exception.nested = false;
vcpu->arch.exception_vmexit.pending = false;
}
--
2.43.0