2023-01-28 08:29:04

by Anup Patel

Subject: [PATCH v3 1/2] RISC-V: KVM: Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()

The kvm_riscv_vcpu_trap_redirect() should set guest privilege mode
to supervisor mode because guest traps/interrupts are always handled
in virtual supervisor mode.

Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU")
Signed-off-by: Anup Patel <[email protected]>
---
arch/riscv/kvm/vcpu_exit.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index c9f741ab26f5..af7c4bc07929 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;
}

/*
--
2.34.1

2023-01-28 08:29:09

by Anup Patel

Subject: [PATCH v3 2/2] RISC-V: KVM: Redirect illegal instruction traps to guest

From: Andy Chiu <[email protected]>

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 <[email protected]>
Signed-off-by: Anup Patel <[email protected]>
Reviewed-by: Andrew Jones <[email protected]>
---
arch/riscv/kvm/vcpu_exit.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index af7c4bc07929..4ea101a73d8b 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -182,6 +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

2023-01-28 13:12:43

by Andrew Jones

Subject: Re: [PATCH v3 1/2] RISC-V: KVM: Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()

On Sat, Jan 28, 2023 at 01:58:46PM +0530, Anup Patel wrote:
> The kvm_riscv_vcpu_trap_redirect() should set guest privilege mode
> to supervisor mode because guest traps/interrupts are always handled
> in virtual supervisor mode.
>
> Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU")
> Signed-off-by: Anup Patel <[email protected]>
> ---
> arch/riscv/kvm/vcpu_exit.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index c9f741ab26f5..af7c4bc07929 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;
> }
>
> /*
> --
> 2.34.1
>

Reviewed-by: Andrew Jones <[email protected]>

Thanks,
drew

2023-01-31 08:46:32

by Atish Patra

Subject: Re: [PATCH v3 2/2] RISC-V: KVM: Redirect illegal instruction traps to guest

On Sat, Jan 28, 2023 at 12:29 AM Anup Patel <[email protected]> wrote:
>
> From: Andy Chiu <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Anup Patel <[email protected]>
> Reviewed-by: Andrew Jones <[email protected]>
> ---
> arch/riscv/kvm/vcpu_exit.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index af7c4bc07929..4ea101a73d8b 100644
> --- a/arch/riscv/kvm/vcpu_exit.c
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -182,6 +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
>

Reviewed-by: Atish Patra <[email protected]>

--
Regards,
Atish

2023-01-31 08:46:58

by Atish Patra

Subject: Re: [PATCH v3 1/2] RISC-V: KVM: Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()

On Sat, Jan 28, 2023 at 12:28 AM Anup Patel <[email protected]> wrote:
>
> The kvm_riscv_vcpu_trap_redirect() should set guest privilege mode
> to supervisor mode because guest traps/interrupts are always handled
> in virtual supervisor mode.
>
> Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU")
> Signed-off-by: Anup Patel <[email protected]>
> ---
> arch/riscv/kvm/vcpu_exit.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index c9f741ab26f5..af7c4bc07929 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;
> }
>
> /*
> --
> 2.34.1
>

Reviewed-by: Atish Patra <[email protected]>

--
Regards,
Atish

2023-02-02 08:50:03

by Anup Patel

Subject: Re: [PATCH v3 1/2] RISC-V: KVM: Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()

On Sat, Jan 28, 2023 at 1:58 PM Anup Patel <[email protected]> wrote:
>
> The kvm_riscv_vcpu_trap_redirect() should set guest privilege mode
> to supervisor mode because guest traps/interrupts are always handled
> in virtual supervisor mode.
>
> Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU")
> Signed-off-by: Anup Patel <[email protected]>

Queued this patch for Linux-6.3

Thanks,
Anup

> ---
> arch/riscv/kvm/vcpu_exit.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index c9f741ab26f5..af7c4bc07929 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;
> }
>
> /*
> --
> 2.34.1
>

2023-02-02 08:50:10

by Anup Patel

Subject: Re: [PATCH v3 2/2] RISC-V: KVM: Redirect illegal instruction traps to guest

On Sat, Jan 28, 2023 at 1:59 PM Anup Patel <[email protected]> wrote:
>
> From: Andy Chiu <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Anup Patel <[email protected]>
> Reviewed-by: Andrew Jones <[email protected]>

Queued this patch for Linux-6.3

Thanks,
Anup

> ---
> arch/riscv/kvm/vcpu_exit.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> index af7c4bc07929..4ea101a73d8b 100644
> --- a/arch/riscv/kvm/vcpu_exit.c
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -182,6 +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
>