linux-kernel - [PATCH 2/6] RISC-V: KVM: Introduce feature specific reset for SBI FWFT

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Message-ID: <20250814155548.457172-3-apatel@ventanamicro.com>
Date: Thu, 14 Aug 2025 21:25:44 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Atish Patra <atish.patra@...ux.dev>
Cc: Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Alexandre Ghiti <alex@...ti.fr>,
	Andrew Jones <ajones@...tanamicro.com>,
	Anup Patel <anup@...infault.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Shuah Khan <shuah@...nel.org>,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	Anup Patel <apatel@...tanamicro.com>
Subject: [PATCH 2/6] RISC-V: KVM: Introduce feature specific reset for SBI FWFT

The SBI FWFT feature values must be reset upon VCPU reset so
introduce feature specific reset callback for this purpose.

Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/kvm/vcpu_sbi_fwft.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
index 164a01288b0a..5a3bad0f9330 100644
--- a/arch/riscv/kvm/vcpu_sbi_fwft.c
+++ b/arch/riscv/kvm/vcpu_sbi_fwft.c
@@ -30,6 +30,13 @@ struct kvm_sbi_fwft_feature {
 	 */
 	bool (*supported)(struct kvm_vcpu *vcpu);
 
+	/**
+	 * @reset: Reset the feature value irrespective whether feature is supported or not
+	 *
+	 * This callback is mandatory
+	 */
+	void (*reset)(struct kvm_vcpu *vcpu);
+
 	/**
 	 * @set: Set the feature value
 	 *
@@ -75,6 +82,13 @@ static bool kvm_sbi_fwft_misaligned_delegation_supported(struct kvm_vcpu *vcpu)
 	return misaligned_traps_can_delegate();
 }
 
+static void kvm_sbi_fwft_reset_misaligned_delegation(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
+
+	cfg->hedeleg &= ~MIS_DELEG;
+}
+
 static long kvm_sbi_fwft_set_misaligned_delegation(struct kvm_vcpu *vcpu,
 					struct kvm_sbi_fwft_config *conf,
 					unsigned long value)
@@ -124,6 +138,11 @@ static bool kvm_sbi_fwft_pointer_masking_pmlen_supported(struct kvm_vcpu *vcpu)
 	return fwft->have_vs_pmlen_7 || fwft->have_vs_pmlen_16;
 }
 
+static void kvm_sbi_fwft_reset_pointer_masking_pmlen(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.cfg.henvcfg &= ~ENVCFG_PMM;
+}
+
 static long kvm_sbi_fwft_set_pointer_masking_pmlen(struct kvm_vcpu *vcpu,
 						   struct kvm_sbi_fwft_config *conf,
 						   unsigned long value)
@@ -180,6 +199,7 @@ static const struct kvm_sbi_fwft_feature features[] = {
 	{
 		.id = SBI_FWFT_MISALIGNED_EXC_DELEG,
 		.supported = kvm_sbi_fwft_misaligned_delegation_supported,
+		.reset = kvm_sbi_fwft_reset_misaligned_delegation,
 		.set = kvm_sbi_fwft_set_misaligned_delegation,
 		.get = kvm_sbi_fwft_get_misaligned_delegation,
 	},
@@ -187,6 +207,7 @@ static const struct kvm_sbi_fwft_feature features[] = {
 	{
 		.id = SBI_FWFT_POINTER_MASKING_PMLEN,
 		.supported = kvm_sbi_fwft_pointer_masking_pmlen_supported,
+		.reset = kvm_sbi_fwft_reset_pointer_masking_pmlen,
 		.set = kvm_sbi_fwft_set_pointer_masking_pmlen,
 		.get = kvm_sbi_fwft_get_pointer_masking_pmlen,
 	},
@@ -321,11 +342,16 @@ static void kvm_sbi_ext_fwft_deinit(struct kvm_vcpu *vcpu)
 
 static void kvm_sbi_ext_fwft_reset(struct kvm_vcpu *vcpu)
 {
-	int i;
 	struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu);
+	const struct kvm_sbi_fwft_feature *feature;
+	int i;
 
-	for (i = 0; i < ARRAY_SIZE(features); i++)
+	for (i = 0; i < ARRAY_SIZE(features); i++) {
 		fwft->configs[i].flags = 0;
+		feature = &features[i];
+		if (feature->reset)
+			feature->reset(vcpu);
+	}
 }
 
 const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft = {
-- 
2.43.0