[PATCH v2 1/3] RISC-V: KVM: Implement kvm_arch_vcpu_ioctl_set_guest_debug()
Anup Patel
anup at brainfault.org
Thu Feb 29 20:30:23 PST 2024
On Fri, Mar 1, 2024 at 7:08 AM Chao Du <duchao at eswincomputing.com> wrote:
>
> kvm_vm_ioctl_check_extension(): Return 1 if KVM_CAP_SET_GUEST_DEBUG is
> been checked.
>
> kvm_arch_vcpu_ioctl_set_guest_debug(): Update the guest_debug flags
> from userspace accordingly. Route the breakpoint exceptions to HS mode
> if the VCPU is being debugged by userspace, by clearing the
> corresponding bit in hedeleg. Write the actual CSR in
> kvm_arch_vcpu_load().
>
> Signed-off-by: Chao Du <duchao at eswincomputing.com>
> ---
> arch/riscv/include/asm/kvm_host.h | 17 +++++++++++++++++
> arch/riscv/include/uapi/asm/kvm.h | 1 +
> arch/riscv/kvm/main.c | 18 ++----------------
> arch/riscv/kvm/vcpu.c | 15 +++++++++++++--
> arch/riscv/kvm/vm.c | 1 +
> 5 files changed, 34 insertions(+), 18 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 484d04a92fa6..9ee3f03ba5d1 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -43,6 +43,22 @@
> KVM_ARCH_REQ_FLAGS(5, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> #define KVM_REQ_STEAL_UPDATE KVM_ARCH_REQ(6)
>
> +#define KVM_HEDELEG_DEFAULT ((_AC(1, UL) << EXC_INST_MISALIGNED) | \
> + (_AC(1, UL) << EXC_BREAKPOINT) | \
> + (_AC(1, UL) << EXC_SYSCALL) | \
> + (_AC(1, UL) << EXC_INST_PAGE_FAULT) | \
> + (_AC(1, UL) << EXC_LOAD_PAGE_FAULT) | \
> + (_AC(1, UL) << EXC_STORE_PAGE_FAULT))
Use BIT(xyz) here. For example: BIT(EXC_INST_MISALIGNED)
Also, BIT(EXC_BREAKPOINT) should not be part of KVM_HEDELEG_DEFAULT.
> +#define KVM_HEDELEG_GUEST_DEBUG ((_AC(1, UL) << EXC_INST_MISALIGNED) | \
> + (_AC(1, UL) << EXC_SYSCALL) | \
> + (_AC(1, UL) << EXC_INST_PAGE_FAULT) | \
> + (_AC(1, UL) << EXC_LOAD_PAGE_FAULT) | \
> + (_AC(1, UL) << EXC_STORE_PAGE_FAULT))
No need for KVM_HEDELEG_GUEST_DEBUG, see below.
> +
> +#define KVM_HIDELEG_DEFAULT ((_AC(1, UL) << IRQ_VS_SOFT) | \
> + (_AC(1, UL) << IRQ_VS_TIMER) | \
> + (_AC(1, UL) << IRQ_VS_EXT))
> +
Same as above, use BIT(xyz) here.
> enum kvm_riscv_hfence_type {
> KVM_RISCV_HFENCE_UNKNOWN = 0,
> KVM_RISCV_HFENCE_GVMA_VMID_GPA,
> @@ -169,6 +185,7 @@ struct kvm_vcpu_csr {
> struct kvm_vcpu_config {
> u64 henvcfg;
> u64 hstateen0;
> + unsigned long hedeleg;
> };
>
> struct kvm_vcpu_smstateen_csr {
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index 7499e88a947c..39f4f4b9dede 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -17,6 +17,7 @@
>
> #define __KVM_HAVE_IRQ_LINE
> #define __KVM_HAVE_READONLY_MEM
> +#define __KVM_HAVE_GUEST_DEBUG
>
> #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
>
> diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> index 225a435d9c9a..bab2ec34cd87 100644
> --- a/arch/riscv/kvm/main.c
> +++ b/arch/riscv/kvm/main.c
> @@ -22,22 +22,8 @@ long kvm_arch_dev_ioctl(struct file *filp,
>
> int kvm_arch_hardware_enable(void)
> {
> - unsigned long hideleg, hedeleg;
> -
> - hedeleg = 0;
> - hedeleg |= (1UL << EXC_INST_MISALIGNED);
> - hedeleg |= (1UL << EXC_BREAKPOINT);
> - hedeleg |= (1UL << EXC_SYSCALL);
> - hedeleg |= (1UL << EXC_INST_PAGE_FAULT);
> - hedeleg |= (1UL << EXC_LOAD_PAGE_FAULT);
> - hedeleg |= (1UL << EXC_STORE_PAGE_FAULT);
> - csr_write(CSR_HEDELEG, hedeleg);
> -
> - hideleg = 0;
> - hideleg |= (1UL << IRQ_VS_SOFT);
> - hideleg |= (1UL << IRQ_VS_TIMER);
> - hideleg |= (1UL << IRQ_VS_EXT);
> - csr_write(CSR_HIDELEG, hideleg);
> + csr_write(CSR_HEDELEG, KVM_HEDELEG_DEFAULT);
> + csr_write(CSR_HIDELEG, KVM_HIDELEG_DEFAULT);
>
> /* VS should access only the time counter directly. Everything else should trap */
> csr_write(CSR_HCOUNTEREN, 0x02);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index b5ca9f2e98ac..242076c2227f 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -475,8 +475,15 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
> int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> struct kvm_guest_debug *dbg)
> {
> - /* TODO; To be implemented later. */
> - return -EINVAL;
if (vcpu->arch.ran_atleast_once)
return -EBUSY;
> + if (dbg->control & KVM_GUESTDBG_ENABLE) {
> + vcpu->guest_debug = dbg->control;
> + vcpu->arch.cfg.hedeleg = KVM_HEDELEG_GUEST_DEBUG;
> + } else {
> + vcpu->guest_debug = 0;
> + vcpu->arch.cfg.hedeleg = KVM_HEDELEG_DEFAULT;
> + }
Don't update vcpu->arch.cfg.hedeleg here since it should be only done
in kvm_riscv_vcpu_setup_config().
> +
> + return 0;
> }
>
> static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
> @@ -505,6 +512,9 @@ static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
> if (riscv_isa_extension_available(isa, SMSTATEEN))
> cfg->hstateen0 |= SMSTATEEN0_SSTATEEN0;
> }
> +
> + if (!vcpu->guest_debug)
> + cfg->hedeleg = KVM_HEDELEG_DEFAULT;
This should be:
cfg->hedeleg = KVM_HEDELEG_DEFAULT;
if (vcpu->guest_debug)
cfg->hedeleg |= BIT(EXC_BREAKPOINT);
> }
>
> void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> @@ -519,6 +529,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> csr_write(CSR_VSEPC, csr->vsepc);
> csr_write(CSR_VSCAUSE, csr->vscause);
> csr_write(CSR_VSTVAL, csr->vstval);
> + csr_write(CSR_HEDELEG, cfg->hedeleg);
> csr_write(CSR_HVIP, csr->hvip);
> csr_write(CSR_VSATP, csr->vsatp);
> csr_write(CSR_HENVCFG, cfg->henvcfg);
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> index ce58bc48e5b8..7396b8654f45 100644
> --- a/arch/riscv/kvm/vm.c
> +++ b/arch/riscv/kvm/vm.c
> @@ -186,6 +186,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_READONLY_MEM:
> case KVM_CAP_MP_STATE:
> case KVM_CAP_IMMEDIATE_EXIT:
> + case KVM_CAP_SET_GUEST_DEBUG:
> r = 1;
> break;
> case KVM_CAP_NR_VCPUS:
> --
> 2.17.1
>
Regards,
Anup
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