KVM: RISC-V: refactor vector state reset

Do not depend on the reset structures.

vector.datap is a kernel memory pointer that needs to be preserved as it
is not a part of the guest vector data.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
Link: https://lore.kernel.org/r/20250403112522.1566629-4-rkrcmar@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>

Author: radimkrcmar

arch/riscv/include/asm/kvm_vcpu_vector.h

@@ -33,8 +33,7 @@ void kvm_riscv_vcpu_guest_vector_restore(struct kvm_cpu_context *cntx,
 					 unsigned long *isa);
 void kvm_riscv_vcpu_host_vector_save(struct kvm_cpu_context *cntx);
 void kvm_riscv_vcpu_host_vector_restore(struct kvm_cpu_context *cntx);
-int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu,
-					struct kvm_cpu_context *cntx);
+int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_free_vector_context(struct kvm_vcpu *vcpu);
 #else
 
@@ -62,8 +61,7 @@ static inline void kvm_riscv_vcpu_host_vector_restore(struct kvm_cpu_context *cn
 {
 }
 
-static inline int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu,
-						      struct kvm_cpu_context *cntx)
+static inline int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu)
 {
 	return 0;
 }

arch/riscv/kvm/vcpu.c

@@ -57,6 +57,7 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 	struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
 	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
 	struct kvm_cpu_context *reset_cntx = &vcpu->arch.guest_reset_context;
+	void *vector_datap = cntx->vector.datap;
 	bool loaded;
 
 	/**
@@ -81,6 +82,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 
 	kvm_riscv_vcpu_fp_reset(vcpu);
 
+	/* Restore datap as it's not a part of the guest context. */
+	cntx->vector.datap = vector_datap;
 	kvm_riscv_vcpu_vector_reset(vcpu);
 
 	kvm_riscv_vcpu_timer_reset(vcpu);
@@ -145,7 +148,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	cntx->hstatus |= HSTATUS_SPV;
 	spin_unlock(&vcpu->arch.reset_cntx_lock);
 
-	if (kvm_riscv_vcpu_alloc_vector_context(vcpu, cntx))
+	if (kvm_riscv_vcpu_alloc_vector_context(vcpu))
 		return -ENOMEM;
 
 	/* By default, make CY, TM, and IR counters accessible in VU mode */

arch/riscv/kvm/vcpu_vector.c

@@ -22,6 +22,9 @@ void kvm_riscv_vcpu_vector_reset(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
 
 	cntx->sstatus &= ~SR_VS;
+
+	cntx->vector.vlenb = riscv_v_vsize / 32;
+
 	if (riscv_isa_extension_available(isa, v)) {
 		cntx->sstatus |= SR_VS_INITIAL;
 		WARN_ON(!cntx->vector.datap);
@@ -70,13 +73,11 @@ void kvm_riscv_vcpu_host_vector_restore(struct kvm_cpu_context *cntx)
 		__kvm_riscv_vector_restore(cntx);
 }
 
-int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu,
-					struct kvm_cpu_context *cntx)
+int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu)
 {
-	cntx->vector.datap = kmalloc(riscv_v_vsize, GFP_KERNEL);
-	if (!cntx->vector.datap)
+	vcpu->arch.guest_context.vector.datap = kzalloc(riscv_v_vsize, GFP_KERNEL);
+	if (!vcpu->arch.guest_context.vector.datap)
 		return -ENOMEM;
-	cntx->vector.vlenb = riscv_v_vsize / 32;
 
 	vcpu->arch.host_context.vector.datap = kzalloc(riscv_v_vsize, GFP_KERNEL);
 	if (!vcpu->arch.host_context.vector.datap)
@@ -87,7 +88,7 @@ int kvm_riscv_vcpu_alloc_vector_context(struct kvm_vcpu *vcpu,
 
 void kvm_riscv_vcpu_free_vector_context(struct kvm_vcpu *vcpu)
 {
-	kfree(vcpu->arch.guest_reset_context.vector.datap);
+	kfree(vcpu->arch.guest_context.vector.datap);
 	kfree(vcpu->arch.host_context.vector.datap);
 }
 #endif