Re: [Qemu-devel] [QEMU 6/7] kvm: Add two new arch specific functions

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jun 13, 2016 at 06:16:48PM +0800, Liang Li wrote:
> Add a new function to get the vm's max pfn and a new function
> to filter out the holes to get a tight free page bitmap.
> They are implemented on X86, and all the arches should implement
> them for live migration optimization.
> 
> Signed-off-by: Liang Li <liang.z.li@intel.com>
> ---
>  include/sysemu/kvm.h |  2 ++
>  target-arm/kvm.c     | 14 ++++++++++++++
>  target-i386/kvm.c    | 35 +++++++++++++++++++++++++++++++++++
>  target-mips/kvm.c    | 14 ++++++++++++++
>  target-ppc/kvm.c     | 14 ++++++++++++++
>  target-s390x/kvm.c   | 14 ++++++++++++++
>  6 files changed, 93 insertions(+)
> 
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index ad6f837..50915f9 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -230,6 +230,8 @@ int kvm_remove_breakpoint(CPUState *cpu, target_ulong addr,
>                            target_ulong len, int type);
>  void kvm_remove_all_breakpoints(CPUState *cpu);
>  int kvm_update_guest_debug(CPUState *cpu, unsigned long reinject_trap);
> +unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap);
> +unsigned long get_guest_max_pfn(void);
>  #ifndef _WIN32
>  int kvm_set_signal_mask(CPUState *cpu, const sigset_t *sigset);
>  #endif
> diff --git a/target-arm/kvm.c b/target-arm/kvm.c
> index 83da447..6464542 100644
> --- a/target-arm/kvm.c
> +++ b/target-arm/kvm.c
> @@ -627,3 +627,17 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      return (data - 32) & 0xffff;
>  }
> +
> +unsigned long get_guest_max_pfn(void)
> +{
> +    /* To be done */
> +
> +    return 0;
> +}
> +
> +unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
> +{
> +    /* To be done */
> +
> +    return bmap;
> +}
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index abf50e6..0b394cb 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -3327,3 +3327,38 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      abort();
>  }
> +
> +unsigned long get_guest_max_pfn(void)
> +{
> +    PCMachineState *pcms = PC_MACHINE(current_machine);
> +    ram_addr_t above_4g_mem = pcms->above_4g_mem_size;
> +    unsigned long max_pfn;
> +
> +    if (above_4g_mem) {
> +        max_pfn = ((1ULL << 32) + above_4g_mem) >> TARGET_PAGE_BITS;
> +    } else {
> +        max_pfn = pcms->below_4g_mem_size >> TARGET_PAGE_BITS;
> +    }
> +
> +    return max_pfn;
> +}

Why is this in kvm?

> +
> +unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
> +{
> +    PCMachineState *pcms = PC_MACHINE(current_machine);
> +    ram_addr_t above_4g_mem = pcms->above_4g_mem_size;
> +
> +    if (above_4g_mem) {
> +        unsigned long *src, *dst, len, pos;
> +        ram_addr_t below_4g_mem = pcms->below_4g_mem_size;
> +        src = bmap + ((1ULL << 32) >> TARGET_PAGE_BITS) / BITS_PER_LONG;
> +        dst = bmap + (below_4g_mem >> TARGET_PAGE_BITS) / BITS_PER_LONG;
> +        bitmap_move(dst, src, above_4g_mem >> TARGET_PAGE_BITS);
> +
> +        pos = (above_4g_mem + below_4g_mem) >> TARGET_PAGE_BITS;
> +        len = ((1ULL << 32) - below_4g_mem) >> TARGET_PAGE_BITS;
> +        bitmap_clear(bmap, pos, len);
> +    }
> +
> +    return bmap;
> +}

what does this do? External APIs should have documentation.

> diff --git a/target-mips/kvm.c b/target-mips/kvm.c
> index a854e4d..89a54e5 100644
> --- a/target-mips/kvm.c
> +++ b/target-mips/kvm.c
> @@ -1048,3 +1048,17 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      abort();
>  }
> +
> +unsigned long get_guest_max_pfn(void)
> +{
> +    /* To be done */
> +
> +    return 0;
> +}
> +
> +unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
> +{
> +    /* To be done */
> +
> +    return bmap;
> +}
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index 24d6032..e222b31 100644
> --- a/target-ppc/kvm.c
> +++ b/target-ppc/kvm.c
> @@ -2579,3 +2579,17 @@ int kvmppc_enable_hwrng(void)
>  
>      return kvmppc_enable_hcall(kvm_state, H_RANDOM);
>  }
> +
> +unsigned long get_guest_max_pfn(void)
> +{
> +    /* To be done */
> +
> +    return 0;
> +}
> +
> +unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
> +{
> +    /* To be done */
> +
> +    return bmap;
> +}
> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> index 8f46fd0..893755b 100644
> --- a/target-s390x/kvm.c
> +++ b/target-s390x/kvm.c
> @@ -2271,3 +2271,17 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      abort();
>  }
> +
> +unsigned long get_guest_max_pfn(void)
> +{
> +    /* To be done */
> +
> +    return 0;
> +}
> +
> +unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
> +{
> +    /* To be done */
> +
> +    return bmap;
> +}
> -- 
> 1.9.1