linux-kernel - [PATCH 5.16 044/126] RISC-V: KVM: make CY, TM, and IR counters accessible in VU mode

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Message-Id: <20220207103805.643776076@linuxfoundation.org>
Date:   Mon,  7 Feb 2022 12:06:15 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mayuresh Chitale <mchitale@...tanamicro.com>,
        Anup Patel <anup@...infault.org>
Subject: [PATCH 5.16 044/126] RISC-V: KVM: make CY, TM, and IR counters accessible in VU mode

From: Mayuresh Chitale <mchitale@...tanamicro.com>

commit de1d7b6a51dab546160d252e47baa54adf104d4a upstream.

Those applications that run in VU mode and access the time CSR cause
a virtual instruction trap as Guest kernel currently does not
initialize the scounteren CSR.

To fix this, we should make CY, TM, and IR counters accessibile
by default in VU mode (similar to OpenSBI).

Fixes: a33c72faf2d73 ("RISC-V: KVM: Implement VCPU create, init and
destroy functions")
Cc: stable@...r.kernel.org
Signed-off-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Anup Patel <anup@...infault.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/riscv/kvm/vcpu.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -74,6 +74,7 @@ int kvm_arch_vcpu_precreate(struct kvm *
 int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpu_context *cntx;
+	struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
 
 	/* Mark this VCPU never ran */
 	vcpu->arch.ran_atleast_once = false;
@@ -89,6 +90,9 @@ int kvm_arch_vcpu_create(struct kvm_vcpu
 	cntx->hstatus |= HSTATUS_SPVP;
 	cntx->hstatus |= HSTATUS_SPV;
 
+	/* By default, make CY, TM, and IR counters accessible in VU mode */
+	reset_csr->scounteren = 0x7;
+
 	/* Setup VCPU timer */
 	kvm_riscv_vcpu_timer_init(vcpu);