linux-kernel - [v2 10/10] RISC-V: KVM: Support 64 bit firmware counters on RV32

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Message-Id: <20231229214950.4061381-11-atishp@rivosinc.com>
Date: Fri, 29 Dec 2023 13:49:50 -0800
From: Atish Patra <atishp@...osinc.com>
To: linux-kernel@...r.kernel.org
Cc: Atish Patra <atishp@...osinc.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	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>,
	Heiko Stuebner <heiko@...ech.de>,
	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: [v2 10/10] 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 |  4 ++-
 arch/riscv/kvm/vcpu_pmu.c             | 37 ++++++++++++++++++++++++++-
 arch/riscv/kvm/vcpu_sbi_pmu.c         |  6 +++++
 3 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
index af6d0ff5ce41..463c349a9ea5 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;
+	u64 value;
 
 	/* Event monitoring status */
 	bool started;
@@ -91,6 +91,8 @@ 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);
+int kvm_riscv_vcpu_pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+				      struct kvm_vcpu_sbi_return *retdata);
 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 f2bf5b5bdd61..e6ce37819ca2 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -196,6 +196,29 @@ static int pmu_get_pmc_index(struct kvm_pmu *pmu, unsigned long eidx,
 	return kvm_pmu_get_programmable_pmc_index(pmu, eidx, cbase, cmask);
 }
 
+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;
+	int fevent_code;
+
+	if (!IS_ENABLED(CONFIG_32BIT))
+		return -EINVAL;
+
+	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;
+}
+
 static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 			unsigned long *out_val)
 {
@@ -701,6 +724,18 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
 	return 0;
 }
 
+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;
+}
+
 int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 				struct kvm_vcpu_sbi_return *retdata)
 {
@@ -774,7 +809,7 @@ 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 9f61136e4bb1..58a0e5587e2a 100644
--- a/arch/riscv/kvm/vcpu_sbi_pmu.c
+++ b/arch/riscv/kvm/vcpu_sbi_pmu.c
@@ -64,6 +64,12 @@ 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 (IS_ENABLED(CONFIG_32BIT))
+			ret = kvm_riscv_vcpu_pmu_fw_ctr_read_hi(vcpu, cp->a0, retdata);
+		else
+			retdata->out_val = 0;
+		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