diff options
| author | Anup Patel <anup.patel@wdc.com> | 2021-09-27 17:10:06 +0530 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2021-10-04 15:51:47 +0530 |
| commit | 9f7013265112a92340cef5debec8d02ec8d1de06 (patch) | |
| tree | 4f77126d24e2124aa992f910012f49ce260602fa /arch/riscv/kvm/vcpu_switch.S | |
| parent | 34bde9d8b9e6e5249db3c07cf1ebfe75c23c671c (diff) | |
RISC-V: KVM: Handle MMIO exits for VCPU
We will get stage2 page faults whenever Guest/VM access SW emulated
MMIO device or unmapped Guest RAM.
This patch implements MMIO read/write emulation by extracting MMIO
details from the trapped load/store instruction and forwarding the
MMIO read/write to user-space. The actual MMIO emulation will happen
in user-space and KVM kernel module will only take care of register
updates before resuming the trapped VCPU.
The handling for stage2 page faults for unmapped Guest RAM will be
implemeted by a separate patch later.
[jiangyifei: ioeventfd and in-kernel mmio device support]
Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/kvm/vcpu_switch.S')
| -rw-r--r-- | arch/riscv/kvm/vcpu_switch.S | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S index 5174b025ff4e..e22721e1b892 100644 --- a/arch/riscv/kvm/vcpu_switch.S +++ b/arch/riscv/kvm/vcpu_switch.S @@ -201,3 +201,26 @@ __kvm_switch_return: /* Return to C code */ ret ENDPROC(__kvm_riscv_switch_to) + +ENTRY(__kvm_riscv_unpriv_trap) + /* + * We assume that faulting unpriv load/store instruction is + * 4-byte long and blindly increment SEPC by 4. + * + * The trap details will be saved at address pointed by 'A0' + * register and we use 'A1' register as temporary. + */ + csrr a1, CSR_SEPC + REG_S a1, (KVM_ARCH_TRAP_SEPC)(a0) + addi a1, a1, 4 + csrw CSR_SEPC, a1 + csrr a1, CSR_SCAUSE + REG_S a1, (KVM_ARCH_TRAP_SCAUSE)(a0) + csrr a1, CSR_STVAL + REG_S a1, (KVM_ARCH_TRAP_STVAL)(a0) + csrr a1, CSR_HTVAL + REG_S a1, (KVM_ARCH_TRAP_HTVAL)(a0) + csrr a1, CSR_HTINST + REG_S a1, (KVM_ARCH_TRAP_HTINST)(a0) + sret +ENDPROC(__kvm_riscv_unpriv_trap) |