>>From: Fangyu Yu <fangyu.yu@xxxxxxxxxxxxxxxxx>
>>
>>When executing HLV* instructions at the HS mode, a guest page fault
>>may occur when a g-stage page table migration between triggering the
>>virtual instruction exception and executing the HLV* instruction.
>>
>>This may be a corner case, and one simpler way to handle this is to
>>re-execute the instruction where the virtual instruction exception
>>occurred, and the guest page fault will be automatically handled.
>>
>>Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU")
>>Signed-off-by: Fangyu Yu <fangyu.yu@xxxxxxxxxxxxxxxxx>
>>---
>> arch/riscv/kvm/vcpu_insn.c | 21 ++++++++++++++++++---
>> 1 file changed, 18 insertions(+), 3 deletions(-)
>>
>>diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c
>>index 97dec18e6989..a8b93aa4d8ec 100644
>>--- a/arch/riscv/kvm/vcpu_insn.c
>>+++ b/arch/riscv/kvm/vcpu_insn.c
>>@@ -448,7 +448,12 @@ int kvm_riscv_vcpu_virtual_insn(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> insn = kvm_riscv_vcpu_unpriv_read(vcpu, true,
>> ct->sepc,
>> &utrap);
>>- if (utrap.scause) {
>>+ switch (utrap.scause) {
>>+ case 0:
>>+ break;
>>+ case EXC_LOAD_GUEST_PAGE_FAULT:
>>+ return KVM_INSN_CONTINUE_SAME_SEPC;
>>+ default:
>> utrap.sepc = ct->sepc;
>> kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
>> return 1;
>>@@ -503,7 +508,12 @@ int kvm_riscv_vcpu_mmio_load(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> */
>> insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
>> &utrap);
>>- if (utrap.scause) {
>>+ switch (utrap.scause) {
>>+ case 0:
>>+ break;
>>+ case EXC_LOAD_GUEST_PAGE_FAULT:
>>+ return KVM_INSN_CONTINUE_SAME_SEPC;
>>+ default:
>> /* Redirect trap if we failed to read instruction */
>> utrap.sepc = ct->sepc;
>> kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
>>@@ -629,7 +639,12 @@ int kvm_riscv_vcpu_mmio_store(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> */
>> insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
>> &utrap);
>>- if (utrap.scause) {
>>+ switch (utrap.scause) {
>>+ case 0:
>>+ break;
>>+ case EXC_LOAD_GUEST_PAGE_FAULT:
>
>Here should be EXC_STORE_GUEST_PAGE_FAULT, I will fix it next version.
Please ignore this comment, EXC_LOAD_GUEST_PAGE_FAULT is correct.
>
>>+ return KVM_INSN_CONTINUE_SAME_SEPC;
>>+ default:
>> /* Redirect trap if we failed to read instruction */
>> utrap.sepc = ct->sepc;
>> kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
>>--
>>2.49.0
>
