* [PATCH v2] RISC-V: KVM: Redirect illegal instruction traps to guest
@ 2023-01-27 11:29 ` Anup Patel
0 siblings, 0 replies; 4+ messages in thread
From: Anup Patel @ 2023-01-27 11:29 UTC (permalink / raw)
To: Paolo Bonzini, Atish Patra
Cc: Palmer Dabbelt, Paul Walmsley, Andrew Jones, Anup Patel, kvm,
kvm-riscv, linux-riscv, linux-kernel, Andy Chiu, Anup Patel
From: Andy Chiu <andy.chiu@sifive.com>
The M-mode redirects an unhandled illegal instruction trap back
to S-mode. However, KVM running in HS-mode terminates the VS-mode
software when it receives illegal instruction trap. Instead, KVM
should redirect the illegal instruction trap back to VS-mode, and
let VS-mode trap handler decide the next step. This futher allows
guest kernel to implement on-demand enabling of vector extension
for a guest user space process upon first-use.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
arch/riscv/kvm/vcpu_exit.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index c9f741ab26f5..4ea101a73d8b 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -160,6 +160,9 @@ void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
/* Set Guest PC to Guest exception vector */
vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
+
+ /* Set Guest privilege mode to supervisor */
+ vcpu->arch.guest_context.sstatus |= SR_SPP;
}
/*
@@ -179,6 +182,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
ret = -EFAULT;
run->exit_reason = KVM_EXIT_UNKNOWN;
switch (trap->scause) {
+ case EXC_INST_ILLEGAL:
+ if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV) {
+ kvm_riscv_vcpu_trap_redirect(vcpu, trap);
+ ret = 1;
+ }
+ break;
case EXC_VIRTUAL_INST_FAULT:
if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
ret = kvm_riscv_vcpu_virtual_insn(vcpu, run, trap);
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2] RISC-V: KVM: Redirect illegal instruction traps to guest
@ 2023-01-27 11:29 ` Anup Patel
0 siblings, 0 replies; 4+ messages in thread
From: Anup Patel @ 2023-01-27 11:29 UTC (permalink / raw)
To: Paolo Bonzini, Atish Patra
Cc: Palmer Dabbelt, Paul Walmsley, Andrew Jones, Anup Patel, kvm,
kvm-riscv, linux-riscv, linux-kernel, Andy Chiu, Anup Patel
From: Andy Chiu <andy.chiu@sifive.com>
The M-mode redirects an unhandled illegal instruction trap back
to S-mode. However, KVM running in HS-mode terminates the VS-mode
software when it receives illegal instruction trap. Instead, KVM
should redirect the illegal instruction trap back to VS-mode, and
let VS-mode trap handler decide the next step. This futher allows
guest kernel to implement on-demand enabling of vector extension
for a guest user space process upon first-use.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
arch/riscv/kvm/vcpu_exit.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index c9f741ab26f5..4ea101a73d8b 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -160,6 +160,9 @@ void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
/* Set Guest PC to Guest exception vector */
vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
+
+ /* Set Guest privilege mode to supervisor */
+ vcpu->arch.guest_context.sstatus |= SR_SPP;
}
/*
@@ -179,6 +182,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
ret = -EFAULT;
run->exit_reason = KVM_EXIT_UNKNOWN;
switch (trap->scause) {
+ case EXC_INST_ILLEGAL:
+ if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV) {
+ kvm_riscv_vcpu_trap_redirect(vcpu, trap);
+ ret = 1;
+ }
+ break;
case EXC_VIRTUAL_INST_FAULT:
if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
ret = kvm_riscv_vcpu_virtual_insn(vcpu, run, trap);
--
2.34.1
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] RISC-V: KVM: Redirect illegal instruction traps to guest
2023-01-27 11:29 ` Anup Patel
@ 2023-01-27 12:05 ` Andrew Jones
-1 siblings, 0 replies; 4+ messages in thread
From: Andrew Jones @ 2023-01-27 12:05 UTC (permalink / raw)
To: Anup Patel
Cc: Paolo Bonzini, Atish Patra, Palmer Dabbelt, Paul Walmsley,
Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel, Andy Chiu
On Fri, Jan 27, 2023 at 04:59:34PM +0530, Anup Patel wrote:
> From: Andy Chiu <andy.chiu@sifive.com>
>
> The M-mode redirects an unhandled illegal instruction trap back
> to S-mode. However, KVM running in HS-mode terminates the VS-mode
> software when it receives illegal instruction trap. Instead, KVM
> should redirect the illegal instruction trap back to VS-mode, and
> let VS-mode trap handler decide the next step. This futher allows
> guest kernel to implement on-demand enabling of vector extension
> for a guest user space process upon first-use.
>
> Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
> arch/riscv/kvm/vcpu_exit.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index c9f741ab26f5..4ea101a73d8b 100644
> --- a/arch/riscv/kvm/vcpu_exit.c
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -160,6 +160,9 @@ void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
>
> /* Set Guest PC to Guest exception vector */
> vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
> +
> + /* Set Guest privilege mode to supervisor */
> + vcpu->arch.guest_context.sstatus |= SR_SPP;
This could/should be a separate fix patch, right?
> }
>
> /*
> @@ -179,6 +182,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> ret = -EFAULT;
> run->exit_reason = KVM_EXIT_UNKNOWN;
> switch (trap->scause) {
> + case EXC_INST_ILLEGAL:
> + if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV) {
> + kvm_riscv_vcpu_trap_redirect(vcpu, trap);
> + ret = 1;
> + }
> + break;
> case EXC_VIRTUAL_INST_FAULT:
> if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
> ret = kvm_riscv_vcpu_virtual_insn(vcpu, run, trap);
> --
> 2.34.1
>
Otherwise,
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Thanks,
drew
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] RISC-V: KVM: Redirect illegal instruction traps to guest
@ 2023-01-27 12:05 ` Andrew Jones
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Jones @ 2023-01-27 12:05 UTC (permalink / raw)
To: Anup Patel
Cc: Paolo Bonzini, Atish Patra, Palmer Dabbelt, Paul Walmsley,
Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel, Andy Chiu
On Fri, Jan 27, 2023 at 04:59:34PM +0530, Anup Patel wrote:
> From: Andy Chiu <andy.chiu@sifive.com>
>
> The M-mode redirects an unhandled illegal instruction trap back
> to S-mode. However, KVM running in HS-mode terminates the VS-mode
> software when it receives illegal instruction trap. Instead, KVM
> should redirect the illegal instruction trap back to VS-mode, and
> let VS-mode trap handler decide the next step. This futher allows
> guest kernel to implement on-demand enabling of vector extension
> for a guest user space process upon first-use.
>
> Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
> arch/riscv/kvm/vcpu_exit.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index c9f741ab26f5..4ea101a73d8b 100644
> --- a/arch/riscv/kvm/vcpu_exit.c
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -160,6 +160,9 @@ void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
>
> /* Set Guest PC to Guest exception vector */
> vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
> +
> + /* Set Guest privilege mode to supervisor */
> + vcpu->arch.guest_context.sstatus |= SR_SPP;
This could/should be a separate fix patch, right?
> }
>
> /*
> @@ -179,6 +182,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> ret = -EFAULT;
> run->exit_reason = KVM_EXIT_UNKNOWN;
> switch (trap->scause) {
> + case EXC_INST_ILLEGAL:
> + if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV) {
> + kvm_riscv_vcpu_trap_redirect(vcpu, trap);
> + ret = 1;
> + }
> + break;
> case EXC_VIRTUAL_INST_FAULT:
> if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
> ret = kvm_riscv_vcpu_virtual_insn(vcpu, run, trap);
> --
> 2.34.1
>
Otherwise,
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Thanks,
drew
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-01-27 13:01 UTC | newest]
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2023-01-27 11:29 [PATCH v2] RISC-V: KVM: Redirect illegal instruction traps to guest Anup Patel
2023-01-27 11:29 ` Anup Patel
2023-01-27 12:05 ` Andrew Jones
2023-01-27 12:05 ` Andrew Jones
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