On Fri, Jun 13, 2025 at 5:08 PM <zhouquan@xxxxxxxxxxx> wrote:
>
> From: Quan Zhou <zhouquan@xxxxxxxxxxx>
>
> Enable ring-based dirty memory tracking on riscv:
>
> - Enable CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL as riscv is weakly
> ordered.
> - Set KVM_DIRTY_LOG_PAGE_OFFSET for the ring buffer's physical page
> offset.
> - Add a check to kvm_vcpu_kvm_riscv_check_vcpu_requests for checking
> whether the dirty ring is soft full.
>
> To handle vCPU requests that cause exits to userspace, modified the
> `kvm_riscv_check_vcpu_requests` to return a value (currently only
> returns 0 or 1).
>
> Signed-off-by: Quan Zhou <zhouquan@xxxxxxxxxxx>
LGTM.
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Queued this patch for Linux-6.17
Thanks,
Anup
> ---
> Documentation/virt/kvm/api.rst | 2 +-
> arch/riscv/include/uapi/asm/kvm.h | 1 +
> arch/riscv/kvm/Kconfig | 1 +
> arch/riscv/kvm/vcpu.c | 18 ++++++++++++++++--
> 4 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 1bd2d42e6424..5de0fbfe2fc0 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -8316,7 +8316,7 @@ core crystal clock frequency, if a non-zero CPUID 0x15 is exposed to the guest.
> 7.36 KVM_CAP_DIRTY_LOG_RING/KVM_CAP_DIRTY_LOG_RING_ACQ_REL
> ----------------------------------------------------------
>
> -:Architectures: x86, arm64
> +:Architectures: x86, arm64, riscv
> :Type: vm
> :Parameters: args[0] - size of the dirty log ring
>
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index 5f59fd226cc5..ef27d4289da1 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -18,6 +18,7 @@
> #define __KVM_HAVE_IRQ_LINE
>
> #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> +#define KVM_DIRTY_LOG_PAGE_OFFSET 64
>
> #define KVM_INTERRUPT_SET -1U
> #define KVM_INTERRUPT_UNSET -2U
> diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
> index 704c2899197e..5a62091b0809 100644
> --- a/arch/riscv/kvm/Kconfig
> +++ b/arch/riscv/kvm/Kconfig
> @@ -25,6 +25,7 @@ config KVM
> select HAVE_KVM_MSI
> select HAVE_KVM_VCPU_ASYNC_IOCTL
> select HAVE_KVM_READONLY_MEM
> + select HAVE_KVM_DIRTY_RING_ACQ_REL
> select KVM_COMMON
> select KVM_GENERIC_DIRTYLOG_READ_PROTECT
> select KVM_GENERIC_HARDWARE_ENABLING
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index e0a01af426ff..0502125efb30 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -690,7 +690,14 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> }
> }
>
> -static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
> +/**
> + * check_vcpu_requests - check and handle pending vCPU requests
> + * @vcpu: the VCPU pointer
> + *
> + * Return: 1 if we should enter the guest
> + * 0 if we should exit to userspace
> + */
> +static int kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
> {
> struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
>
> @@ -735,7 +742,12 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
>
> if (kvm_check_request(KVM_REQ_STEAL_UPDATE, vcpu))
> kvm_riscv_vcpu_record_steal_time(vcpu);
> +
> + if (kvm_dirty_ring_check_request(vcpu))
> + return 0;
> }
> +
> + return 1;
> }
>
> static void kvm_riscv_update_hvip(struct kvm_vcpu *vcpu)
> @@ -917,7 +929,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>
> kvm_riscv_gstage_vmid_update(vcpu);
>
> - kvm_riscv_check_vcpu_requests(vcpu);
> + ret = kvm_riscv_check_vcpu_requests(vcpu);
> + if (ret <= 0)
> + continue;
>
> preempt_disable();
>
> --
> 2.34.1
>
