Re: [PATCH v4 14/21] KVM: arm64: Support SDEI_EVENT_{COMPLETE, COMPLETE_AND_RESUME} hypercall
From: Gavin Shan
Date: Wed Jan 12 2022 - 01:43:52 EST
Hi Eric,
On 11/10/21 6:58 PM, Eric Auger wrote:
On 8/15/21 2:13 AM, Gavin Shan wrote:
This supports SDEI_EVENT_{COMPLETE, COMPLETE_AND_RESUME} hypercall.
They are used by the guest to notify the completion of the SDEI
event in the handler. The registers are changed according to the
SDEI specification as below:
* x0 - x17, PC and PState are restored to what values we had in
the interrupted context.
* If it's SDEI_EVENT_COMPLETE_AND_RESUME hypercall, IRQ exception
is injected.
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_emulate.h | 1 +
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/kvm/hyp/exception.c | 7 +++
arch/arm64/kvm/inject_fault.c | 27 ++++++++++
arch/arm64/kvm/sdei.c | 75 ++++++++++++++++++++++++++++
5 files changed, 111 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index fd418955e31e..923b4d08ea9a 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -37,6 +37,7 @@ bool kvm_condition_valid32(const struct kvm_vcpu *vcpu);
void kvm_skip_instr32(struct kvm_vcpu *vcpu);
void kvm_inject_undefined(struct kvm_vcpu *vcpu);
+void kvm_inject_irq(struct kvm_vcpu *vcpu);
void kvm_inject_vabt(struct kvm_vcpu *vcpu);
void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 46f363aa6524..1824f7e1f9ab 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -437,6 +437,7 @@ struct kvm_vcpu_arch {
#define KVM_ARM64_EXCEPT_AA32_UND (0 << 9)
#define KVM_ARM64_EXCEPT_AA32_IABT (1 << 9)
#define KVM_ARM64_EXCEPT_AA32_DABT (2 << 9)
+#define KVM_ARM64_EXCEPT_AA32_IRQ (3 << 9)
/* For AArch64: */
#define KVM_ARM64_EXCEPT_AA64_ELx_SYNC (0 << 9)
#define KVM_ARM64_EXCEPT_AA64_ELx_IRQ (1 << 9)
diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c
index 0418399e0a20..ef458207d152 100644
--- a/arch/arm64/kvm/hyp/exception.c
+++ b/arch/arm64/kvm/hyp/exception.c
@@ -310,6 +310,9 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu)
case KVM_ARM64_EXCEPT_AA32_DABT:
enter_exception32(vcpu, PSR_AA32_MODE_ABT, 16);
break;
+ case KVM_ARM64_EXCEPT_AA32_IRQ:
+ enter_exception32(vcpu, PSR_AA32_MODE_IRQ, 4);
+ break;
default:
/* Err... */
break;
@@ -320,6 +323,10 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu)
KVM_ARM64_EXCEPT_AA64_EL1):
enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync);
break;
+ case (KVM_ARM64_EXCEPT_AA64_ELx_IRQ |
+ KVM_ARM64_EXCEPT_AA64_EL1):
+ enter_exception64(vcpu, PSR_MODE_EL1h, except_type_irq);
+ break;
default:
/*
* Only EL1_SYNC makes sense so far, EL2_{SYNC,IRQ}
diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index b47df73e98d7..3a8c55867d2f 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -66,6 +66,13 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
}
+static void inject_irq64(struct kvm_vcpu *vcpu)
+{
+ vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA64_EL1 |
+ KVM_ARM64_EXCEPT_AA64_ELx_IRQ |
+ KVM_ARM64_PENDING_EXCEPTION);
+}
+
#define DFSR_FSC_EXTABT_LPAE 0x10
#define DFSR_FSC_EXTABT_nLPAE 0x08
#define DFSR_LPAE BIT(9)
@@ -77,6 +84,12 @@ static void inject_undef32(struct kvm_vcpu *vcpu)
KVM_ARM64_PENDING_EXCEPTION);
}
+static void inject_irq32(struct kvm_vcpu *vcpu)
+{
+ vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA32_IRQ |
+ KVM_ARM64_PENDING_EXCEPTION);
+}
+
/*
* Modelled after TakeDataAbortException() and TakePrefetchAbortException
* pseudocode.
@@ -160,6 +173,20 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu)
inject_undef64(vcpu);
}
+/**
+ * kvm_inject_irq - inject an IRQ into the guest
+ *
+ * It is assumed that this code is called from the VCPU thread and that the
+ * VCPU therefore is not currently executing guest code.
+ */
+void kvm_inject_irq(struct kvm_vcpu *vcpu)
+{
+ if (vcpu_el1_is_32bit(vcpu))
+ inject_irq32(vcpu);
+ else
+ inject_irq64(vcpu);
+}
+
void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 esr)
{
vcpu_set_vsesr(vcpu, esr & ESR_ELx_ISS_MASK);
diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
index b5d6d1ed3858..1e8e213c9d70 100644
--- a/arch/arm64/kvm/sdei.c
+++ b/arch/arm64/kvm/sdei.c
@@ -308,6 +308,75 @@ static unsigned long kvm_sdei_hypercall_context(struct kvm_vcpu *vcpu)
return ret;
}
+static unsigned long kvm_sdei_hypercall_complete(struct kvm_vcpu *vcpu,
+ bool resume)
+{
+ struct kvm *kvm = vcpu->kvm;
+ struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
+ struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
+ struct kvm_sdei_kvm_event *kske = NULL;
+ struct kvm_sdei_vcpu_event *ksve = NULL;
+ struct kvm_sdei_vcpu_regs *regs;
+ unsigned long ret = SDEI_SUCCESS;
for the RESUME you never seem to read resume_addr arg? How does it work?
I don't get the irq injection path. Please could you explain?
The guest kernel uses COMPLETE and COMPLETE_AND_RESUME hypercalls to notify the
SDEI event has been acknoledged by it. The difference between them is COMPLETE_AND_RESUME
fires the pending interrupts, but COMPLETE doesn't.
+ int index;
+
+ /* Sanity check */
+ if (!(ksdei && vsdei)) {
+ ret = SDEI_NOT_SUPPORTED;
+ goto out;
+ }
+
+ spin_lock(&vsdei->lock);
+ if (vsdei->critical_event) {
+ ksve = vsdei->critical_event;
+ regs = &vsdei->state.critical_regs;
+ vsdei->critical_event = NULL;
+ vsdei->state.critical_num = KVM_SDEI_INVALID_NUM;
+ } else if (vsdei->normal_event) {
+ ksve = vsdei->normal_event;
+ regs = &vsdei->state.normal_regs;
+ vsdei->normal_event = NULL;
+ vsdei->state.normal_num = KVM_SDEI_INVALID_NUM;
+ } else {
+ ret = SDEI_DENIED;
+ goto unlock;
+ }
+
+ /* Restore registers: x0 -> x17, PC, PState */
+ for (index = 0; index < ARRAY_SIZE(regs->regs); index++)
+ vcpu_set_reg(vcpu, index, regs->regs[index]);
+
+ *vcpu_cpsr(vcpu) = regs->pstate;
+ *vcpu_pc(vcpu) = regs->pc;
+
+ /* Inject interrupt if needed */
+ if (resume)
+ kvm_inject_irq(vcpu);
+
+ /*
+ * Update state. We needn't take lock in order to update the KVM
+ * event state as it's not destroyed because of the reference
+ * count.
+ */
+ kske = ksve->kske;
+ ksve->state.refcount--;
+ kske->state.refcount--;
why double --?
On each SDEI event is queued for delivery, both reference count are increased. I guess
it's a bit confusing. I will change in next revision:
ksve->state.refcount: Increased on each SDEI event is queued for delivered
kske->state.refcount: Increased on each @ksve is created
+ if (!ksve->state.refcount) {
why not using a struct kref directly?
The reason is kref isn't friendly to userspace. This field (@refcount) needs to be
migrated :)
+ list_del(&ksve->link);
+ kfree(ksve);
+ }
+
+ /* Make another request if there is pending event */
+ if (!(list_empty(&vsdei->critical_events) &&
+ list_empty(&vsdei->normal_events)))
+ kvm_make_request(KVM_REQ_SDEI, vcpu);
+
+unlock:
+ spin_unlock(&vsdei->lock);
+out:
+ return ret;
+}
+
static unsigned long kvm_sdei_hypercall_unregister(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
@@ -628,7 +697,13 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
ret = kvm_sdei_hypercall_context(vcpu);
break;
case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
+ has_result = false;
+ ret = kvm_sdei_hypercall_complete(vcpu, false);
+ break;
case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
+ has_result = false;
+ ret = kvm_sdei_hypercall_complete(vcpu, true);
+ break;
case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
ret = kvm_sdei_hypercall_unregister(vcpu);
break;
Thanks,
Gavin