linux-kernel - Re: [PATCH v2 07/12] RISC-V: KVM: Use ncsr_xyz() in kvm_riscv_vcpu_trap

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Message-ID: <f60715b1-3d15-4929-95c6-f21b433c14c5@linux.dev>
Date: Fri, 13 Jun 2025 17:46:38 -0700
From: Atish Patra <atish.patra@...ux.dev>
To: Anup Patel <apatel@...tanamicro.com>
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>,
 kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 07/12] RISC-V: KVM: Use ncsr_xyz() in
 kvm_riscv_vcpu_trap_redirect()


On 6/12/25 11:57 PM, Anup Patel wrote:
> The H-extension CSRs accessed by kvm_riscv_vcpu_trap_redirect() will
> trap when KVM RISC-V is running as Guest/VM hence remove these traps
> by using ncsr_xyz() instead of csr_xyz().
>
> Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> ---
>   arch/riscv/kvm/vcpu_exit.c | 13 +++++++------
>   1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index 6e0c18412795..85c43c83e3b9 100644
> --- a/arch/riscv/kvm/vcpu_exit.c
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -9,6 +9,7 @@
>   #include <linux/kvm_host.h>
>   #include <asm/csr.h>
>   #include <asm/insn-def.h>
> +#include <asm/kvm_nacl.h>
>   
>   static int gstage_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
>   			     struct kvm_cpu_trap *trap)
> @@ -135,7 +136,7 @@ unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
>   void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
>   				  struct kvm_cpu_trap *trap)
>   {
> -	unsigned long vsstatus = csr_read(CSR_VSSTATUS);
> +	unsigned long vsstatus = ncsr_read(CSR_VSSTATUS);
>   
>   	/* Change Guest SSTATUS.SPP bit */
>   	vsstatus &= ~SR_SPP;
> @@ -151,15 +152,15 @@ void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
>   	vsstatus &= ~SR_SIE;
>   
>   	/* Update Guest SSTATUS */
> -	csr_write(CSR_VSSTATUS, vsstatus);
> +	ncsr_write(CSR_VSSTATUS, vsstatus);
>   
>   	/* Update Guest SCAUSE, STVAL, and SEPC */
> -	csr_write(CSR_VSCAUSE, trap->scause);
> -	csr_write(CSR_VSTVAL, trap->stval);
> -	csr_write(CSR_VSEPC, trap->sepc);
> +	ncsr_write(CSR_VSCAUSE, trap->scause);
> +	ncsr_write(CSR_VSTVAL, trap->stval);
> +	ncsr_write(CSR_VSEPC, trap->sepc);
>   
>   	/* Set Guest PC to Guest exception vector */
> -	vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
> +	vcpu->arch.guest_context.sepc = ncsr_read(CSR_VSTVEC);
>   
>   	/* Set Guest privilege mode to supervisor */
>   	vcpu->arch.guest_context.sstatus |= SR_SPP;


Reviewed-by: Atish Patra <atishp@...osinc.com>