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authorAnup Patel <anup.patel@wdc.com>2021-09-27 14:40:07 +0300
committerAnup Patel <anup@brainfault.org>2021-10-04 13:25:01 +0300
commit5a5d79acd7daebeb813a7c0654ca91c5ea7c228e (patch)
treeeb389e40031e2ab24b9d4244f52d4e4a9b7268ef /arch/riscv/kvm/vcpu_exit.c
parent9f7013265112a92340cef5debec8d02ec8d1de06 (diff)
downloadlinux-5a5d79acd7daebeb813a7c0654ca91c5ea7c228e.tar.xz
RISC-V: KVM: Handle WFI exits for VCPU
We get illegal instruction trap whenever Guest/VM executes WFI instruction. This patch handles WFI trap by blocking the trapped VCPU using kvm_vcpu_block() API. The blocked VCPU will be automatically resumed whenever a VCPU interrupt is injected from user-space or from in-kernel IRQCHIP emulation. Signed-off-by: Anup Patel <anup.patel@wdc.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/kvm/vcpu_exit.c')
-rw-r--r--arch/riscv/kvm/vcpu_exit.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index dc66be032ad7..f659be94231d 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -12,6 +12,13 @@
#include <linux/kvm_host.h>
#include <asm/csr.h>
+#define INSN_OPCODE_MASK 0x007c
+#define INSN_OPCODE_SHIFT 2
+#define INSN_OPCODE_SYSTEM 28
+
+#define INSN_MASK_WFI 0xffffffff
+#define INSN_MATCH_WFI 0x10500073
+
#define INSN_MATCH_LB 0x3
#define INSN_MASK_LB 0x707f
#define INSN_MATCH_LH 0x1003
@@ -116,6 +123,71 @@
(s32)(((insn) >> 7) & 0x1f))
#define MASK_FUNCT3 0x7000
+static int truly_illegal_insn(struct kvm_vcpu *vcpu,
+ struct kvm_run *run,
+ ulong insn)
+{
+ struct kvm_cpu_trap utrap = { 0 };
+
+ /* Redirect trap to Guest VCPU */
+ utrap.sepc = vcpu->arch.guest_context.sepc;
+ utrap.scause = EXC_INST_ILLEGAL;
+ utrap.stval = insn;
+ kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+
+ return 1;
+}
+
+static int system_opcode_insn(struct kvm_vcpu *vcpu,
+ struct kvm_run *run,
+ ulong insn)
+{
+ if ((insn & INSN_MASK_WFI) == INSN_MATCH_WFI) {
+ vcpu->stat.wfi_exit_stat++;
+ if (!kvm_arch_vcpu_runnable(vcpu)) {
+ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+ kvm_vcpu_block(vcpu);
+ vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_clear_request(KVM_REQ_UNHALT, vcpu);
+ }
+ vcpu->arch.guest_context.sepc += INSN_LEN(insn);
+ return 1;
+ }
+
+ return truly_illegal_insn(vcpu, run, insn);
+}
+
+static int virtual_inst_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
+ struct kvm_cpu_trap *trap)
+{
+ unsigned long insn = trap->stval;
+ struct kvm_cpu_trap utrap = { 0 };
+ struct kvm_cpu_context *ct;
+
+ if (unlikely(INSN_IS_16BIT(insn))) {
+ if (insn == 0) {
+ ct = &vcpu->arch.guest_context;
+ insn = kvm_riscv_vcpu_unpriv_read(vcpu, true,
+ ct->sepc,
+ &utrap);
+ if (utrap.scause) {
+ utrap.sepc = ct->sepc;
+ kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+ return 1;
+ }
+ }
+ if (INSN_IS_16BIT(insn))
+ return truly_illegal_insn(vcpu, run, insn);
+ }
+
+ switch ((insn & INSN_OPCODE_MASK) >> INSN_OPCODE_SHIFT) {
+ case INSN_OPCODE_SYSTEM:
+ return system_opcode_insn(vcpu, run, insn);
+ default:
+ return truly_illegal_insn(vcpu, run, insn);
+ }
+}
+
static int emulate_load(struct kvm_vcpu *vcpu, struct kvm_run *run,
unsigned long fault_addr, unsigned long htinst)
{
@@ -596,6 +668,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
ret = -EFAULT;
run->exit_reason = KVM_EXIT_UNKNOWN;
switch (trap->scause) {
+ case EXC_VIRTUAL_INST_FAULT:
+ if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
+ ret = virtual_inst_fault(vcpu, run, trap);
+ break;
case EXC_INST_GUEST_PAGE_FAULT:
case EXC_LOAD_GUEST_PAGE_FAULT:
case EXC_STORE_GUEST_PAGE_FAULT: