MIPS: KVM: Add MSA exception handling
Add guest exception handling for MIPS SIMD Architecture (MSA) floating
point exceptions and MSA disabled exceptions.
MSA floating point exceptions from the guest need passing to the guest
kernel, so for these a guest MSAFPE is emulated.
MSA disabled exceptions are normally handled by passing a reserved
instruction exception to the guest (because no guest MSA was supported),
but the hypervisor can now handle them if the guest has MSA by passing
an MSA disabled exception to the guest, or if the guest has MSA enabled
by transparently restoring the guest MSA context and enabling MSA and
the FPU.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 1dc0dca..4c25823 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -123,7 +123,9 @@
u32 resvd_inst_exits;
u32 break_inst_exits;
u32 trap_inst_exits;
+ u32 msa_fpe_exits;
u32 fpe_exits;
+ u32 msa_disabled_exits;
u32 flush_dcache_exits;
u32 halt_successful_poll;
u32 halt_wakeup;
@@ -144,7 +146,9 @@
RESVD_INST_EXITS,
BREAK_INST_EXITS,
TRAP_INST_EXITS,
+ MSA_FPE_EXITS,
FPE_EXITS,
+ MSA_DISABLED_EXITS,
FLUSH_DCACHE_EXITS,
MAX_KVM_MIPS_EXIT_TYPES
};
@@ -305,6 +309,7 @@
*/
#define T_TRAP 13 /* Trap instruction */
#define T_VCEI 14 /* Virtual coherency exception */
+#define T_MSAFPE 14 /* MSA floating point exception */
#define T_FPE 15 /* Floating point exception */
#define T_MSADIS 21 /* MSA disabled exception */
#define T_WATCH 23 /* Watch address reference */
@@ -601,6 +606,7 @@
int (*handle_res_inst)(struct kvm_vcpu *vcpu);
int (*handle_break)(struct kvm_vcpu *vcpu);
int (*handle_trap)(struct kvm_vcpu *vcpu);
+ int (*handle_msa_fpe)(struct kvm_vcpu *vcpu);
int (*handle_fpe)(struct kvm_vcpu *vcpu);
int (*handle_msa_disabled)(struct kvm_vcpu *vcpu);
int (*vm_init)(struct kvm *kvm);
@@ -756,11 +762,21 @@
struct kvm_run *run,
struct kvm_vcpu *vcpu);
+extern enum emulation_result kvm_mips_emulate_msafpe_exc(unsigned long cause,
+ uint32_t *opc,
+ struct kvm_run *run,
+ struct kvm_vcpu *vcpu);
+
extern enum emulation_result kvm_mips_emulate_fpe_exc(unsigned long cause,
uint32_t *opc,
struct kvm_run *run,
struct kvm_vcpu *vcpu);
+extern enum emulation_result kvm_mips_emulate_msadis_exc(unsigned long cause,
+ uint32_t *opc,
+ struct kvm_run *run,
+ struct kvm_vcpu *vcpu);
+
extern enum emulation_result kvm_mips_complete_mmio_load(struct kvm_vcpu *vcpu,
struct kvm_run *run);
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index 07f554c..6230f37 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -2179,6 +2179,41 @@
return er;
}
+enum emulation_result kvm_mips_emulate_msafpe_exc(unsigned long cause,
+ uint32_t *opc,
+ struct kvm_run *run,
+ struct kvm_vcpu *vcpu)
+{
+ struct mips_coproc *cop0 = vcpu->arch.cop0;
+ struct kvm_vcpu_arch *arch = &vcpu->arch;
+ enum emulation_result er = EMULATE_DONE;
+
+ if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+ /* save old pc */
+ kvm_write_c0_guest_epc(cop0, arch->pc);
+ kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+ if (cause & CAUSEF_BD)
+ kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+ else
+ kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+ kvm_debug("Delivering MSAFPE @ pc %#lx\n", arch->pc);
+
+ kvm_change_c0_guest_cause(cop0, (0xff),
+ (T_MSAFPE << CAUSEB_EXCCODE));
+
+ /* Set PC to the exception entry point */
+ arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+ } else {
+ kvm_err("Trying to deliver MSAFPE when EXL is already set\n");
+ er = EMULATE_FAIL;
+ }
+
+ return er;
+}
+
enum emulation_result kvm_mips_emulate_fpe_exc(unsigned long cause,
uint32_t *opc,
struct kvm_run *run,
@@ -2214,6 +2249,41 @@
return er;
}
+enum emulation_result kvm_mips_emulate_msadis_exc(unsigned long cause,
+ uint32_t *opc,
+ struct kvm_run *run,
+ struct kvm_vcpu *vcpu)
+{
+ struct mips_coproc *cop0 = vcpu->arch.cop0;
+ struct kvm_vcpu_arch *arch = &vcpu->arch;
+ enum emulation_result er = EMULATE_DONE;
+
+ if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+ /* save old pc */
+ kvm_write_c0_guest_epc(cop0, arch->pc);
+ kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+ if (cause & CAUSEF_BD)
+ kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+ else
+ kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+ kvm_debug("Delivering MSADIS @ pc %#lx\n", arch->pc);
+
+ kvm_change_c0_guest_cause(cop0, (0xff),
+ (T_MSADIS << CAUSEB_EXCCODE));
+
+ /* Set PC to the exception entry point */
+ arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+ } else {
+ kvm_err("Trying to deliver MSADIS when EXL is already set\n");
+ er = EMULATE_FAIL;
+ }
+
+ return er;
+}
+
/* ll/sc, rdhwr, sync emulation */
#define OPCODE 0xfc000000
@@ -2421,6 +2491,7 @@
case T_BREAK:
case T_RES_INST:
case T_TRAP:
+ case T_MSAFPE:
case T_FPE:
case T_MSADIS:
break;
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index a17f210..e02c7e5 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -50,7 +50,9 @@
{ "resvd_inst", VCPU_STAT(resvd_inst_exits), KVM_STAT_VCPU },
{ "break_inst", VCPU_STAT(break_inst_exits), KVM_STAT_VCPU },
{ "trap_inst", VCPU_STAT(trap_inst_exits), KVM_STAT_VCPU },
+ { "msa_fpe", VCPU_STAT(msa_fpe_exits), KVM_STAT_VCPU },
{ "fpe", VCPU_STAT(fpe_exits), KVM_STAT_VCPU },
+ { "msa_disabled", VCPU_STAT(msa_disabled_exits), KVM_STAT_VCPU },
{ "flush_dcache", VCPU_STAT(flush_dcache_exits), KVM_STAT_VCPU },
{ "halt_successful_poll", VCPU_STAT(halt_successful_poll), KVM_STAT_VCPU },
{ "halt_wakeup", VCPU_STAT(halt_wakeup), KVM_STAT_VCPU },
@@ -1256,6 +1258,12 @@
ret = kvm_mips_callbacks->handle_trap(vcpu);
break;
+ case T_MSAFPE:
+ ++vcpu->stat.msa_fpe_exits;
+ trace_kvm_exit(vcpu, MSA_FPE_EXITS);
+ ret = kvm_mips_callbacks->handle_msa_fpe(vcpu);
+ break;
+
case T_FPE:
++vcpu->stat.fpe_exits;
trace_kvm_exit(vcpu, FPE_EXITS);
@@ -1263,6 +1271,8 @@
break;
case T_MSADIS:
+ ++vcpu->stat.msa_disabled_exits;
+ trace_kvm_exit(vcpu, MSA_DISABLED_EXITS);
ret = kvm_mips_callbacks->handle_msa_disabled(vcpu);
break;
diff --git a/arch/mips/kvm/stats.c b/arch/mips/kvm/stats.c
index 3843828..888bb67 100644
--- a/arch/mips/kvm/stats.c
+++ b/arch/mips/kvm/stats.c
@@ -26,7 +26,9 @@
"Reserved Inst",
"Break Inst",
"Trap Inst",
+ "MSA FPE",
"FPE",
+ "MSA Disabled",
"D-Cache Flushes",
};
diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c
index 421d5b8..d836ed5 100644
--- a/arch/mips/kvm/trap_emul.c
+++ b/arch/mips/kvm/trap_emul.c
@@ -362,6 +362,24 @@
return ret;
}
+static int kvm_trap_emul_handle_msa_fpe(struct kvm_vcpu *vcpu)
+{
+ struct kvm_run *run = vcpu->run;
+ uint32_t __user *opc = (uint32_t __user *)vcpu->arch.pc;
+ unsigned long cause = vcpu->arch.host_cp0_cause;
+ enum emulation_result er = EMULATE_DONE;
+ int ret = RESUME_GUEST;
+
+ er = kvm_mips_emulate_msafpe_exc(cause, opc, run, vcpu);
+ if (er == EMULATE_DONE) {
+ ret = RESUME_GUEST;
+ } else {
+ run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+ ret = RESUME_HOST;
+ }
+ return ret;
+}
+
static int kvm_trap_emul_handle_fpe(struct kvm_vcpu *vcpu)
{
struct kvm_run *run = vcpu->run;
@@ -380,16 +398,36 @@
return ret;
}
+/**
+ * kvm_trap_emul_handle_msa_disabled() - Guest used MSA while disabled in root.
+ * @vcpu: Virtual CPU context.
+ *
+ * Handle when the guest attempts to use MSA when it is disabled.
+ */
static int kvm_trap_emul_handle_msa_disabled(struct kvm_vcpu *vcpu)
{
+ struct mips_coproc *cop0 = vcpu->arch.cop0;
struct kvm_run *run = vcpu->run;
uint32_t __user *opc = (uint32_t __user *) vcpu->arch.pc;
unsigned long cause = vcpu->arch.host_cp0_cause;
enum emulation_result er = EMULATE_DONE;
int ret = RESUME_GUEST;
- /* No MSA supported in guest, guest reserved instruction exception */
- er = kvm_mips_emulate_ri_exc(cause, opc, run, vcpu);
+ if (!kvm_mips_guest_has_msa(&vcpu->arch) ||
+ (kvm_read_c0_guest_status(cop0) & (ST0_CU1 | ST0_FR)) == ST0_CU1) {
+ /*
+ * No MSA in guest, or FPU enabled and not in FR=1 mode,
+ * guest reserved instruction exception
+ */
+ er = kvm_mips_emulate_ri_exc(cause, opc, run, vcpu);
+ } else if (!(kvm_read_c0_guest_config5(cop0) & MIPS_CONF5_MSAEN)) {
+ /* MSA disabled by guest, guest MSA disabled exception */
+ er = kvm_mips_emulate_msadis_exc(cause, opc, run, vcpu);
+ } else {
+ /* Restore MSA/FPU state */
+ kvm_own_msa(vcpu);
+ er = EMULATE_DONE;
+ }
switch (er) {
case EMULATE_DONE:
@@ -608,6 +646,7 @@
.handle_res_inst = kvm_trap_emul_handle_res_inst,
.handle_break = kvm_trap_emul_handle_break,
.handle_trap = kvm_trap_emul_handle_trap,
+ .handle_msa_fpe = kvm_trap_emul_handle_msa_fpe,
.handle_fpe = kvm_trap_emul_handle_fpe,
.handle_msa_disabled = kvm_trap_emul_handle_msa_disabled,