linux-kernel - [RFC 9/9] RISC-V: KVM: Support 64 bit firmware counters on RV32

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Message-Id: <20231205024310.1593100-10-atishp@rivosinc.com>
Date:   Mon,  4 Dec 2023 18:43:10 -0800
From:   Atish Patra <atishp@...osinc.com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atishp@...osinc.com>,
        Alexandre Ghiti <alexghiti@...osinc.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Guo Ren <guoren@...nel.org>, Icenowy Zheng <uwu@...nowy.me>,
        kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org,
        linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Will Deacon <will@...nel.org>
Subject: [RFC 9/9] RISC-V: KVM: Support 64 bit firmware counters on RV32

The SBI v2.0 introduced a fw_read_hi function to read 64 bit firmware
counters for RV32 based systems.

Add infrastructure to support that.

Signed-off-by: Atish Patra <atishp@...osinc.com>
---
 arch/riscv/include/asm/kvm_vcpu_pmu.h |  6 ++++-
 arch/riscv/kvm/vcpu_pmu.c             | 38 ++++++++++++++++++++++++++-
 arch/riscv/kvm/vcpu_sbi_pmu.c         |  7 +++++
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
index 64c75acad6ba..dd655315e706 100644
--- a/arch/riscv/include/asm/kvm_vcpu_pmu.h
+++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h
@@ -20,7 +20,7 @@ static_assert(RISCV_KVM_MAX_COUNTERS <= 64);
 
 struct kvm_fw_event {
 	/* Current value of the event */
-	unsigned long value;
+	uint64_t value;
 
 	/* Event monitoring status */
 	bool started;
@@ -91,6 +91,10 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
 				     struct kvm_vcpu_sbi_return *retdata);
 int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 				struct kvm_vcpu_sbi_return *retdata);
+#if defined(CONFIG_32BIT)
+int kvm_riscv_vcpu_pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+				struct kvm_vcpu_sbi_return *retdata);
+#endif
 void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu);
 int kvm_riscv_vcpu_pmu_setup_snapshot(struct kvm_vcpu *vcpu, unsigned long saddr_low,
 				       unsigned long saddr_high, unsigned long flags,
diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 86c8e92f92d3..5b4a93647256 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -195,6 +195,28 @@ static int pmu_get_pmc_index(struct kvm_pmu *pmu, unsigned long eidx,
 
 	return kvm_pmu_get_programmable_pmc_index(pmu, eidx, cbase, cmask);
 }
+#if defined(CONFIG_32BIT)
+static int pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+			      unsigned long *out_val)
+{
+	struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+	struct kvm_pmc *pmc;
+	u64 enabled, running;
+	int fevent_code;
+
+	pmc = &kvpmu->pmc[cidx];
+
+	if (pmc->cinfo.type != SBI_PMU_CTR_TYPE_FW)
+		return -EINVAL;
+
+	fevent_code = get_event_code(pmc->event_idx);
+	pmc->counter_val = kvpmu->fw_event[fevent_code].value;
+
+	*out_val = pmc->counter_val >> 32;
+
+	return 0;
+}
+#endif
 
 static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 			unsigned long *out_val)
@@ -696,6 +718,20 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
 	return 0;
 }
 
+#if defined(CONFIG_32BIT)
+int kvm_riscv_vcpu_pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+				   struct kvm_vcpu_sbi_return *retdata)
+{
+	int ret;
+
+	ret = pmu_fw_ctr_read_hi(vcpu, cidx, &retdata->out_val);
+	if (ret == -EINVAL)
+		retdata->err_val = SBI_ERR_INVALID_PARAM;
+
+	return 0;
+}
+#endif
+
 int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 				struct kvm_vcpu_sbi_return *retdata)
 {
@@ -769,7 +805,7 @@ void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
 			pmc->cinfo.csr = CSR_CYCLE + i;
 		} else {
 			pmc->cinfo.type = SBI_PMU_CTR_TYPE_FW;
-			pmc->cinfo.width = BITS_PER_LONG - 1;
+			pmc->cinfo.width = 63;
 		}
 	}
 
diff --git a/arch/riscv/kvm/vcpu_sbi_pmu.c b/arch/riscv/kvm/vcpu_sbi_pmu.c
index 77c20a61fd7d..0cd051d5a448 100644
--- a/arch/riscv/kvm/vcpu_sbi_pmu.c
+++ b/arch/riscv/kvm/vcpu_sbi_pmu.c
@@ -64,6 +64,13 @@ static int kvm_sbi_ext_pmu_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	case SBI_EXT_PMU_COUNTER_FW_READ:
 		ret = kvm_riscv_vcpu_pmu_ctr_read(vcpu, cp->a0, retdata);
 		break;
+	case SBI_EXT_PMU_COUNTER_FW_READ_HI:
+#if defined(CONFIG_32BIT)
+		ret = kvm_riscv_vcpu_pmu_fw_ctr_read_hi(vcpu, cp->a0, retdata);
+#else
+		retdata->out_val = 0;
+#endif
+		break;
 	case SBI_EXT_PMU_SNAPSHOT_SET_SHMEM:
 		ret = kvm_riscv_vcpu_pmu_setup_snapshot(vcpu, cp->a0, cp->a1, cp->a2, retdata);
 		break;
-- 
2.34.1