Re: [PATCH RFC 2/2] target/kvm: Add interfaces needed for log dirty

[Anup Patel]

On Thu, Aug 27, 2020 at 1:54 PM Yifei Jiang <jiangyifei@xxxxxxxxxx> wrote:
>
> Add two interfaces of log dirty for kvm_main.c, and detele the interface
> kvm_vm_ioctl_get_dirty_log which is redundantly defined.
>
> CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT is added in defconfig.
>
> Signed-off-by: Yifei Jiang <jiangyifei@xxxxxxxxxx>
> Signed-off-by: Yipeng Yin <yinyipeng1@xxxxxxxxxx>
> ---
>  arch/riscv/configs/defconfig |  1 +
>  arch/riscv/kvm/Kconfig       |  1 +
>  arch/riscv/kvm/mmu.c         | 43 ++++++++++++++++++++++++++++++++++++
>  arch/riscv/kvm/vm.c          |  6 -----
>  4 files changed, 45 insertions(+), 6 deletions(-)
>
> diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
> index d36e1000bbd3..857d799672c2 100644
> --- a/arch/riscv/configs/defconfig
> +++ b/arch/riscv/configs/defconfig
> @@ -19,6 +19,7 @@ CONFIG_SOC_VIRT=y
>  CONFIG_SMP=y
>  CONFIG_VIRTUALIZATION=y
>  CONFIG_KVM=y
> +CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT=y
>  CONFIG_HOTPLUG_CPU=y
>  CONFIG_MODULES=y
>  CONFIG_MODULE_UNLOAD=y
> diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
> index 2356dc52ebb3..91fcffc70e5d 100644
> --- a/arch/riscv/kvm/Kconfig
> +++ b/arch/riscv/kvm/Kconfig
> @@ -26,6 +26,7 @@ config KVM
>         select KVM_MMIO
>         select HAVE_KVM_VCPU_ASYNC_IOCTL
>         select SRCU
> +       select KVM_GENERIC_DIRTYLOG_READ_PROTECT
>         help
>           Support hosting virtualized guest machines.
>
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index 88bce80ee983..df2a470c25e4 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -358,6 +358,43 @@ void stage2_wp_memory_region(struct kvm *kvm, int slot)
>         kvm_flush_remote_tlbs(kvm);
>  }
>
> +/**
> + * kvm_mmu_write_protect_pt_masked() - write protect dirty pages
> + * @kvm:    The KVM pointer
> + * @slot:   The memory slot associated with mask
> + * @gfn_offset: The gfn offset in memory slot
> + * @mask:   The mask of dirty pages at offset 'gfn_offset' in this memory
> + *      slot to be write protected
> + *
> + * Walks bits set in mask write protects the associated pte's. Caller must
> + * acquire kvm_mmu_lock.
> + */
> +static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
> +        struct kvm_memory_slot *slot,
> +        gfn_t gfn_offset, unsigned long mask)
> +{
> +    phys_addr_t base_gfn = slot->base_gfn + gfn_offset;
> +    phys_addr_t start = (base_gfn +  __ffs(mask)) << PAGE_SHIFT;
> +    phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
> +
> +    stage2_wp_range(kvm, start, end);
> +}
> +
> +/*
> + * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected
> + * dirty pages.
> + *
> + * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to
> + * enable dirty logging for them.
> + */
> +void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
> +        struct kvm_memory_slot *slot,
> +        gfn_t gfn_offset, unsigned long mask)
> +{
> +    kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
> +}
> +
> +
>  int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
>                    unsigned long size, bool writable)
>  {
> @@ -433,6 +470,12 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
>  {
>  }
>
> +void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
> +                                       struct kvm_memory_slot *memslot)
> +{
> +       kvm_flush_remote_tlbs(kvm);
> +}
> +
>  void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
>  {
>  }
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> index 4f2498198cb5..f7405676903b 100644
> --- a/arch/riscv/kvm/vm.c
> +++ b/arch/riscv/kvm/vm.c
> @@ -12,12 +12,6 @@
>  #include <linux/uaccess.h>
>  #include <linux/kvm_host.h>
>
> -int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
> -{
> -       /* TODO: To be added later. */
> -       return -ENOTSUPP;
> -}
> -
>  int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>  {
>         int r;
> --
> 2.19.1
>
>

I already have a similar change as part of v14 KVM RISC-V series.

Let us coordinate better. Please let us know in-advance for any
KVM RISC-V feature you plan to work on. Otherwise, this leads to
efforts wasted at your end or at our end.

Regards,
Anup