On LoongArch, the host and guest have their own PMU CSRs registers
and they share PMU hardware resources. A set of PMU CSRs consists of
a CTRL register and a CNTR register. We can set which PMU CSRs are used
by the guest by writing to the GCFG register [24: 26] bits.
On KVM side:
- we save the host PMU CSRs into structure kvm_context.
- If the host supports the PMU feature.
- When entering guest mode. we save the host PMU CSRs and restore the guest PMU CSRs.
- When exiting guest mode, we save the guest PMU CSRs and restore the host PMU CSRs.
Signed-off-by: Song Gao <gaosong@xxxxxxxxxxx>
---
V5:
- When restoring the PMU context, resotre the CNTR register before the CTRL register.
- Link to V4: https://lore.kernel.org/all/20240429093401.2612430-1-gaosong@xxxxxxxxxxx/
V4:
- Use the macro kvm_read_clear_hw_gcsr to optimize the code
and remove redundant code.
- Link to V3: https://lore.kernel.org/all/20240424091813.1471440-1-gaosong@xxxxxxxxxxx/
V3:
- When saving the PMU context, clear the CTRL register
before reading the CNTR register.
- Put kvm_lose_pmu() in kvm_handler_exit().
- Link to V2: https://lore.kernel.org/all/20240417065236.500011-1-gaosong@xxxxxxxxxxx/
V2:
- Add new vcpu->request flag KVM_REQ_PMU. If we use PMU,
We need to set this flag;
- Add kvm_check_pmu() to kvm_pre_enter_guest();
- On _kvm_setcsr(), after modifying the PMU CSR register value,
if we use PMU, we need to set KVM_REQ_PMU.
- Link to V1: https://lore.kernel.org/all/20240410095812.2943706-1-gaosong@xxxxxxxxxxx/
arch/loongarch/include/asm/kvm_csr.h | 7 +
arch/loongarch/include/asm/kvm_host.h | 20 +++
arch/loongarch/include/asm/loongarch.h | 1 +
arch/loongarch/kvm/exit.c | 8 ++
arch/loongarch/kvm/vcpu.c | 173 ++++++++++++++++++++++++-
5 files changed, 207 insertions(+), 2 deletions(-)
diff --git a/arch/loongarch/include/asm/kvm_csr.h b/arch/loongarch/include/asm/kvm_csr.h
index 724ca8b7b401..0a52f115a87e 100644
--- a/arch/loongarch/include/asm/kvm_csr.h
+++ b/arch/loongarch/include/asm/kvm_csr.h
@@ -30,6 +30,7 @@
: [val] "+r" (__v) \
: [reg] "i" (csr) \
: "memory"); \
+ __v; \
})
#define gcsr_xchg(v, m, csr) \
@@ -180,6 +181,7 @@ __BUILD_GCSR_OP(tlbidx)
#define kvm_save_hw_gcsr(csr, gid) (csr->csrs[gid] = gcsr_read(gid))
#define kvm_restore_hw_gcsr(csr, gid) (gcsr_write(csr->csrs[gid], gid))
+#define kvm_read_clear_hw_gcsr(csr, gid) (csr->csrs[gid] = gcsr_write(0, gid))
int kvm_emu_iocsr(larch_inst inst, struct kvm_run *run, struct kvm_vcpu *vcpu);
@@ -208,4 +210,9 @@ static __always_inline void kvm_change_sw_gcsr(struct loongarch_csrs *csr,
csr->csrs[gid] |= val & _mask;
}
+#define KVM_PMU_EVENT_ENABLED (CSR_PERFCTRL_PLV0 | \
+ CSR_PERFCTRL_PLV1 | \
+ CSR_PERFCTRL_PLV2 | \
+ CSR_PERFCTRL_PLV3)
+
#endif /* __ASM_LOONGARCH_KVM_CSR_H__ */
diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index 2d62f7b0d377..e1d64e26e7cb 100644
--- a/arch/loongarch/include/asm/kvm_host.h
+++ b/arch/loongarch/include/asm/kvm_host.h
@@ -51,9 +51,14 @@ struct kvm_arch_memory_slot {
unsigned long flags;
};
+#define KVM_REQ_PMU KVM_ARCH_REQ(0)
+#define HOST_MAX_PMNUM 16
struct kvm_context {
unsigned long vpid_cache;
struct kvm_vcpu *last_vcpu;
+ /* Save host pmu csr */
+ u64 perf_ctrl[HOST_MAX_PMNUM];
+ u64 perf_cntr[HOST_MAX_PMNUM];
};
struct kvm_world_switch {
@@ -99,6 +104,8 @@ enum emulation_result {
#define KVM_LARCH_LASX (0x1 << 2)
#define KVM_LARCH_SWCSR_LATEST (0x1 << 3)
#define KVM_LARCH_HWCSR_USABLE (0x1 << 4)
+#define KVM_GUEST_PMU_ENABLE (0x1 << 5)
+#define KVM_GUEST_PMU_ACTIVE (0x1 << 6)
struct kvm_vcpu_arch {
/*
@@ -136,6 +143,9 @@ struct kvm_vcpu_arch {
/* CSR state */
struct loongarch_csrs *csr;
+ /* Guest max PMU CSR id */
+ int max_pmu_csrid;
+
/* GPR used as IO source/target */
u32 io_gpr;
@@ -195,6 +205,16 @@ static inline bool kvm_guest_has_lasx(struct kvm_vcpu_arch *arch)
return arch->cpucfg[2] & CPUCFG2_LASX;
}
+static inline bool kvm_guest_has_pmu(struct kvm_vcpu_arch *arch)
+{
+ return arch->cpucfg[LOONGARCH_CPUCFG6] & CPUCFG6_PMP;
+}
+
+static inline int kvm_get_pmu_num(struct kvm_vcpu_arch *arch)
+{
+ return (arch->cpucfg[LOONGARCH_CPUCFG6] & CPUCFG6_PMNUM) >> CPUCFG6_PMNUM_SHIFT;
+}
+
/* Debug: dump vcpu state */
int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu);
diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
index 46366e783c84..644380b6ebec 100644
--- a/arch/loongarch/include/asm/loongarch.h
+++ b/arch/loongarch/include/asm/loongarch.h
@@ -119,6 +119,7 @@
#define CPUCFG6_PMP BIT(0)
#define CPUCFG6_PAMVER GENMASK(3, 1)
#define CPUCFG6_PMNUM GENMASK(7, 4)
+#define CPUCFG6_PMNUM_SHIFT 4
#define CPUCFG6_PMBITS GENMASK(13, 8)
#define CPUCFG6_UPM BIT(14)
diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index ed1d89d53e2e..636cd1500135 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -83,6 +83,14 @@ static int kvm_handle_csr(struct kvm_vcpu *vcpu, larch_inst inst)
rj = inst.reg2csr_format.rj;
csrid = inst.reg2csr_format.csr;
+ if (csrid >= LOONGARCH_CSR_PERFCTRL0 && csrid <= vcpu->arch.max_pmu_csrid) {
+ if (kvm_guest_has_pmu(&vcpu->arch)) {
+ vcpu->arch.pc -= 4;
+ kvm_make_request(KVM_REQ_PMU, vcpu);
+ return EMULATE_DONE;
+ }
+ }
+
/* Process CSR ops */
switch (rj) {
case 0: /* process csrrd */
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 3a8779065f73..df7ede36755f 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -30,6 +30,131 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
sizeof(kvm_vcpu_stats_desc),
};
+static inline void kvm_save_host_pmu(struct kvm_vcpu *vcpu)
+{
+ struct kvm_context *context;
+
+ context = this_cpu_ptr(vcpu->kvm->arch.vmcs);
+ context->perf_ctrl[0] = write_csr_perfctrl0(0);
+ context->perf_ctrl[1] = write_csr_perfctrl1(0);
+ context->perf_ctrl[2] = write_csr_perfctrl2(0);
+ context->perf_ctrl[3] = write_csr_perfctrl3(0);
+ context->perf_cntr[0] = read_csr_perfcntr0();
+ context->perf_cntr[1] = read_csr_perfcntr1();
+ context->perf_cntr[2] = read_csr_perfcntr2();
+ context->perf_cntr[3] = read_csr_perfcntr3();
+}
+
+static inline void kvm_restore_host_pmu(struct kvm_vcpu *vcpu)
+{
+ struct kvm_context *context;
+
+ context = this_cpu_ptr(vcpu->kvm->arch.vmcs);
+ write_csr_perfcntr0(context->perf_cntr[0]);
+ write_csr_perfcntr1(context->perf_cntr[1]);
+ write_csr_perfcntr2(context->perf_cntr[2]);
+ write_csr_perfcntr3(context->perf_cntr[3]);
+ write_csr_perfctrl0(context->perf_ctrl[0]);
+ write_csr_perfctrl1(context->perf_ctrl[1]);
+ write_csr_perfctrl2(context->perf_ctrl[2]);
+ write_csr_perfctrl3(context->perf_ctrl[3]);
+}
+
+
+static inline void kvm_save_guest_pmu(struct kvm_vcpu *vcpu)
+{
+ struct loongarch_csrs *csr = vcpu->arch.csr;
+
+ kvm_read_clear_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL0);
+ kvm_read_clear_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL1);
+ kvm_read_clear_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL2);
+ kvm_read_clear_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL3);
+ kvm_save_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR0);
+ kvm_save_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR1);
+ kvm_save_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR2);
+ kvm_save_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR3);
+}
+
+static inline void kvm_restore_guest_pmu(struct kvm_vcpu *vcpu)
+{
+ struct loongarch_csrs *csr = vcpu->arch.csr;
+
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR0);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR1);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR2);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCNTR3);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL0);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL1);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL2);
+ kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_PERFCTRL3);
+}
+
+static void kvm_lose_pmu(struct kvm_vcpu *vcpu)
+{
+ unsigned long val;
+ struct loongarch_csrs *csr = vcpu->arch.csr;
+
+ if (!(vcpu->arch.aux_inuse & KVM_GUEST_PMU_ENABLE))
+ return;
+ if (!(vcpu->arch.aux_inuse & KVM_GUEST_PMU_ACTIVE))
+ return;
+
+ kvm_save_guest_pmu(vcpu);
+ /* Disable pmu access from guest */
+ write_csr_gcfg(read_csr_gcfg() & ~CSR_GCFG_GPERF);
+
+ /*
+ * Clear KVM_GUEST_PMU_ENABLE if the guest is not using PMU CSRs
+ * when exiting the guest, so that the next time trap into the guest.
+ * we don't need to deal with PMU CSRs contexts.
+ */
+ val = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL0);
+ val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL1);
+ val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL2);
+ val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL3);
+ if (!(val & KVM_PMU_EVENT_ENABLED))
+ vcpu->arch.aux_inuse &= ~KVM_GUEST_PMU_ENABLE;
+ kvm_restore_host_pmu(vcpu);
+
+ /* KVM_GUEST_PMU_ACTIVE needs to be cleared when exiting the guest */
+ vcpu->arch.aux_inuse &= ~KVM_GUEST_PMU_ACTIVE;
+}
+
+static void kvm_own_pmu(struct kvm_vcpu *vcpu)
+{
+ unsigned long val;
+
+ kvm_save_host_pmu(vcpu);
+ /* Set PM0-PM(num) to guest */
+ val = read_csr_gcfg() & ~CSR_GCFG_GPERF;
+ val |= (kvm_get_pmu_num(&vcpu->arch) + 1) << CSR_GCFG_GPERF_SHIFT;
+ write_csr_gcfg(val);
+ kvm_restore_guest_pmu(vcpu);
+}
+
+static void kvm_restore_pmu(struct kvm_vcpu *vcpu)
+{
+ if (!(vcpu->arch.aux_inuse & KVM_GUEST_PMU_ENABLE))
+ return;
+
+ kvm_make_request(KVM_REQ_PMU, vcpu);
+}
+
+static void kvm_check_pmu(struct kvm_vcpu *vcpu)
+{
+ if (!kvm_check_request(KVM_REQ_PMU, vcpu))
+ return;
+
+ kvm_own_pmu(vcpu);
+
+ /*
+ * Set KVM_GUEST PMU_ENABLE and GUEST_PMU_ACTIVE
+ * when guest has KVM_REQ_PMU request.
+ */
+ vcpu->arch.aux_inuse |= KVM_GUEST_PMU_ENABLE;
+ vcpu->arch.aux_inuse |= KVM_GUEST_PMU_ACTIVE;
+}
+
/*
* kvm_check_requests - check and handle pending vCPU requests
*
@@ -100,6 +225,7 @@ static int kvm_pre_enter_guest(struct kvm_vcpu *vcpu)
/* Make sure the vcpu mode has been written */
smp_store_mb(vcpu->mode, IN_GUEST_MODE);
kvm_check_vpid(vcpu);
+ kvm_check_pmu(vcpu);
vcpu->arch.host_eentry = csr_read64(LOONGARCH_CSR_EENTRY);
/* Clear KVM_LARCH_SWCSR_LATEST as CSR will change when enter guest */
vcpu->arch.aux_inuse &= ~KVM_LARCH_SWCSR_LATEST;
@@ -130,6 +256,8 @@ static int kvm_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
/* Set a default exit reason */
run->exit_reason = KVM_EXIT_UNKNOWN;
+ kvm_lose_pmu(vcpu);
+
guest_timing_exit_irqoff();
guest_state_exit_irqoff();
local_irq_enable();
@@ -295,6 +423,21 @@ static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
kvm_write_sw_gcsr(csr, id, val);
+ /*
+ * After modifying the PMU CSR register value of the vcpu.
+ * If the PMU CSRs are used, we need to set KVM_REQ_PMU.
+ */
+ if (id >= LOONGARCH_CSR_PERFCTRL0 && id <= LOONGARCH_CSR_PERFCNTR3) {
+ unsigned long val;
+
+ val = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL0);
+ val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL1);
+ val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL2);
+ val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL3);
+ if (val & KVM_PMU_EVENT_ENABLED)
+ kvm_make_request(KVM_REQ_PMU, vcpu);
+ }
+
return ret;
}
@@ -333,6 +476,12 @@ static int _kvm_get_cpucfg_mask(int id, u64 *v)
case LOONGARCH_CPUCFG5:
*v = GENMASK(31, 0);
return 0;
+ case LOONGARCH_CPUCFG6:
+ if (cpu_has_pmp)
+ *v = GENMASK(14, 0);
+ else
+ *v = 0;
+ return 0;
case LOONGARCH_CPUCFG16:
*v = GENMASK(16, 0);
return 0;
@@ -351,7 +500,7 @@ static int _kvm_get_cpucfg_mask(int id, u64 *v)
static int kvm_check_cpucfg(int id, u64 val)
{
- int ret;
+ int ret, host;
u64 mask = 0;
ret = _kvm_get_cpucfg_mask(id, &mask);
@@ -377,6 +526,18 @@ static int kvm_check_cpucfg(int id, u64 val)
/* LASX architecturally implies LSX and FP but val does not satisfy that */
return -EINVAL;
return 0;
+ case LOONGARCH_CPUCFG6:
+ if (val & CPUCFG6_PMP) {
+ host = read_cpucfg(LOONGARCH_CPUCFG6);
+ if ((val & CPUCFG6_PMBITS) != (host & CPUCFG6_PMBITS))
+ /* Guest pmbits must be the same with host */
+ return -EINVAL;
+ if ((val & CPUCFG6_PMNUM) > (host & CPUCFG6_PMNUM))
+ return -EINVAL;
+ if ((val & CPUCFG6_UPM) && !(host & CPUCFG6_UPM))
+ return -EINVAL;
+ }
+ return 0;
default:
/*
* Values for the other CPUCFG IDs are not being further validated
@@ -459,6 +620,10 @@ static int kvm_set_one_reg(struct kvm_vcpu *vcpu,
if (ret)
break;
vcpu->arch.cpucfg[id] = (u32)v;
+ if (id == LOONGARCH_CPUCFG6) {
+ vcpu->arch.max_pmu_csrid = LOONGARCH_CSR_PERFCTRL0 +
+ 2 * kvm_get_pmu_num(&vcpu->arch) + 1;
+ }
break;
case KVM_REG_LOONGARCH_KVM:
switch (reg->id) {
@@ -552,7 +717,8 @@ static int kvm_loongarch_cpucfg_has_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr)
{
switch (attr->attr) {
- case 2:
+ case LOONGARCH_CPUCFG2:
+ case LOONGARCH_CPUCFG6:
return 0;
default:
return -ENXIO;
@@ -982,6 +1148,9 @@ static int _kvm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
/* Control guest page CCA attribute */
change_csr_gcfg(CSR_GCFG_MATC_MASK, CSR_GCFG_MATC_ROOT);
+ /* Restore hardware PMU CSRs */
+ kvm_restore_pmu(vcpu);
+
/* Don't bother restoring registers multiple times unless necessary */
if (vcpu->arch.aux_inuse & KVM_LARCH_HWCSR_USABLE)
return 0;
