Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-04 10:01:41 +00:00
Code Issues Packages Projects Releases Wiki Activity

RISC-V: KVM: Add extensible system instruction emulation framework

Browse Source 
We will be emulating more system instructions in near future with
upcoming AIA, PMU, Nested and other virtualization features.

To accommodate above, we add an extensible system instruction emulation
framework in vcpu_insn.c.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Anup Patel 2022-07-29 17:14:46 +05:30 committed by Anup Patel
parent b91f0e4cb8
commit 1222b55cee
2 changed files with 83 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/riscv/include/asm/kvm_vcpu_insn.h
View File

@ -18,6 +18,15 @@ struct kvm_mmio_decode {
int return_handled;
};
/* Return values used by function emulating a particular instruction */
enum kvm_insn_return {
KVM_INSN_EXIT_TO_USER_SPACE = 0,
KVM_INSN_CONTINUE_NEXT_SEPC,
KVM_INSN_CONTINUE_SAME_SEPC,
KVM_INSN_ILLEGAL_TRAP,
KVM_INSN_VIRTUAL_TRAP
};
void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu);
int kvm_riscv_vcpu_virtual_insn(struct kvm_vcpu *vcpu, struct kvm_run *run,
struct kvm_cpu_trap *trap);

84
arch/riscv/kvm/vcpu_insn.c
View File

@ -118,8 +118,24 @@
(s32)(((insn) >> 7) & 0x1f))
#define MASK_FUNCT3 0x7000
static int truly_illegal_insn(struct kvm_vcpu *vcpu,
struct kvm_run *run,
struct insn_func {
unsigned long mask;
unsigned long match;
/*
* Possible return values are as follows:
* 1) Returns < 0 for error case
* 2) Returns 0 for exit to user-space
* 3) Returns 1 to continue with next sepc
* 4) Returns 2 to continue with same sepc
* 5) Returns 3 to inject illegal instruction trap and continue
* 6) Returns 4 to inject virtual instruction trap and continue
*
* Use enum kvm_insn_return for return values
*/
int (*func)(struct kvm_vcpu *vcpu, struct kvm_run *run, ulong insn);
};
static int truly_illegal_insn(struct kvm_vcpu *vcpu, struct kvm_run *run,
ulong insn)
{
struct kvm_cpu_trap utrap = { 0 };
@ -128,6 +144,24 @@ static int truly_illegal_insn(struct kvm_vcpu *vcpu,
utrap.sepc = vcpu->arch.guest_context.sepc;
utrap.scause = EXC_INST_ILLEGAL;
utrap.stval = insn;
utrap.htval = 0;
utrap.htinst = 0;
kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
return 1;
}
static int truly_virtual_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_VIRTUAL_INST_FAULT;
utrap.stval = insn;
utrap.htval = 0;
utrap.htinst = 0;
kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
return 1;
@ -148,18 +182,48 @@ void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu)
}
}
static int system_opcode_insn(struct kvm_vcpu *vcpu,
struct kvm_run *run,
static int wfi_insn(struct kvm_vcpu *vcpu, struct kvm_run *run, ulong insn)
{
vcpu->stat.wfi_exit_stat++;
kvm_riscv_vcpu_wfi(vcpu);
return KVM_INSN_CONTINUE_NEXT_SEPC;
}
static const struct insn_func system_opcode_funcs[] = {
{
.mask = INSN_MASK_WFI,
.match = INSN_MATCH_WFI,
.func = wfi_insn,
},
};
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++;
kvm_riscv_vcpu_wfi(vcpu);
vcpu->arch.guest_context.sepc += INSN_LEN(insn);
return 1;
int i, rc = KVM_INSN_ILLEGAL_TRAP;
const struct insn_func *ifn;
for (i = 0; i < ARRAY_SIZE(system_opcode_funcs); i++) {
ifn = &system_opcode_funcs[i];
if ((insn & ifn->mask) == ifn->match) {
rc = ifn->func(vcpu, run, insn);
break;
}
}
return truly_illegal_insn(vcpu, run, insn);
switch (rc) {
case KVM_INSN_ILLEGAL_TRAP:
return truly_illegal_insn(vcpu, run, insn);
case KVM_INSN_VIRTUAL_TRAP:
return truly_virtual_insn(vcpu, run, insn);
case KVM_INSN_CONTINUE_NEXT_SEPC:
vcpu->arch.guest_context.sepc += INSN_LEN(insn);
break;
default:
break;
}
return (rc <= 0) ? rc : 1;
}
/**