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KVM: arm64: Indicate SYSTEM_RESET2 in kvm_run::system_event flags field

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When handling reset and power-off PSCI calls from the guest, we
initialise X0 to PSCI_RET_INTERNAL_FAILURE in case the VMM tries to
re-run the vCPU after issuing the call.

Unfortunately, this also means that the VMM cannot see which PSCI call
was issued and therefore cannot distinguish between PSCI SYSTEM_RESET
and SYSTEM_RESET2 calls, which is necessary in order to determine the
validity of the "reset_type" in X1.

Allocate bit 0 of the previously unused 'flags' field of the
system_event structure so that we can indicate the PSCI call used to
initiate the reset.

Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220221153524.15397-4-will@kernel.org
This commit is contained in:
Will Deacon 2022-02-21 15:35:24 +00:00 committed by Marc Zyngier
parent d43583b890
commit 34739fd95f
3 changed files with 23 additions and 4 deletions
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5
Documentation/virt/kvm/api.rst
View file

@ -5939,6 +5939,11 @@ Valid values for 'type' are:
to ignore the request, or to gather VM memory core dump and/or
reset/shutdown of the VM.
Valid flags are:
- KVM_SYSTEM_EVENT_RESET_FLAG_PSCI_RESET2 (arm64 only) -- the guest issued
a SYSTEM_RESET2 call according to v1.1 of the PSCI specification.
::
/* KVM_EXIT_IOAPIC_EOI */

7
arch/arm64/include/uapi/asm/kvm.h
View file

@ -413,6 +413,13 @@ struct kvm_arm_copy_mte_tags {
#define KVM_PSCI_RET_INVAL PSCI_RET_INVALID_PARAMS
#define KVM_PSCI_RET_DENIED PSCI_RET_DENIED
/* arm64-specific kvm_run::system_event flags */
/*
* Reset caused by a PSCI v1.1 SYSTEM_RESET2 call.
* Valid only when the system event has a type of KVM_SYSTEM_EVENT_RESET.
*/
#define KVM_SYSTEM_EVENT_RESET_FLAG_PSCI_RESET2 (1ULL << 0)
#endif
#endif /* __ARM_KVM_H__ */

15
arch/arm64/kvm/psci.c
View file

@ -162,7 +162,7 @@ static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
return PSCI_0_2_AFFINITY_LEVEL_OFF;
}
static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type, u64 flags)
{
unsigned long i;
struct kvm_vcpu *tmp;
@ -182,17 +182,24 @@ static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
vcpu->run->system_event.type = type;
vcpu->run->system_event.flags = flags;
vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
}
static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
{
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN, 0);
}
static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
{
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET, 0);
}
static void kvm_psci_system_reset2(struct kvm_vcpu *vcpu)
{
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET,
KVM_SYSTEM_EVENT_RESET_FLAG_PSCI_RESET2);
}
static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
@ -364,7 +371,7 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
arg < PSCI_1_1_RESET_TYPE_VENDOR_START) {
val = PSCI_RET_INVALID_PARAMS;
} else {
kvm_psci_system_reset(vcpu);
kvm_psci_system_reset2(vcpu);
val = PSCI_RET_INTERNAL_FAILURE;
ret = 0;
}