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Re: [PATCH 02/22] x86/setup: move vm_init() before acpi calls



On Fri, 16 Dec 2022, Julien Grall wrote:
> From: Wei Liu <wei.liu2@xxxxxxxxxx>
> 
> After the direct map removal, pages from the boot allocator are not
> mapped at all in the direct map. Although we have map_domain_page, they
> are ephemeral and are less helpful for mappings that are more than a
> page, so we want a mechanism to globally map a range of pages, which is
> what vmap is for. Therefore, we bring vm_init into early boot stage.
> 
> To allow vmap to be initialised and used in early boot, we need to
> modify vmap to receive pages from the boot allocator during early boot
> stage.
> 
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> Signed-off-by: David Woodhouse <dwmw2@xxxxxxxxxx>
> Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx>
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

For the arm and common parts:

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/arch/arm/setup.c |  4 ++--
>  xen/arch/x86/setup.c | 31 ++++++++++++++++++++-----------
>  xen/common/vmap.c    | 37 +++++++++++++++++++++++++++++--------
>  3 files changed, 51 insertions(+), 21 deletions(-)
> 
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index 1f26f67b90e3..2311726f5ddd 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -1028,6 +1028,8 @@ void __init start_xen(unsigned long boot_phys_offset,
>  
>      setup_mm();
>  
> +    vm_init();
> +
>      /* Parse the ACPI tables for possible boot-time configuration */
>      acpi_boot_table_init();
>  
> @@ -1039,8 +1041,6 @@ void __init start_xen(unsigned long boot_phys_offset,
>       */
>      system_state = SYS_STATE_boot;
>  
> -    vm_init();
> -
>      if ( acpi_disabled )
>      {
>          printk("Booting using Device Tree\n");
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 6bb5bc7c84be..1c2e09711eb0 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -870,6 +870,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>      unsigned long eb_start, eb_end;
>      bool acpi_boot_table_init_done = false, relocated = false;
>      int ret;
> +    bool vm_init_done = false;
>      struct ns16550_defaults ns16550 = {
>          .data_bits = 8,
>          .parity    = 'n',
> @@ -1442,12 +1443,23 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>              continue;
>  
>          if ( !acpi_boot_table_init_done &&
> -             s >= (1ULL << 32) &&
> -             !acpi_boot_table_init() )
> +             s >= (1ULL << 32) )
>          {
> -            acpi_boot_table_init_done = true;
> -            srat_parse_regions(s);
> -            setup_max_pdx(raw_max_page);
> +            /*
> +             * We only initialise vmap and acpi after going through the 
> bottom
> +             * 4GiB, so that we have enough pages in the boot allocator.
> +             */
> +            if ( !vm_init_done )
> +            {
> +                vm_init();
> +                vm_init_done = true;
> +            }
> +            if ( !acpi_boot_table_init() )
> +            {
> +                acpi_boot_table_init_done = true;
> +                srat_parse_regions(s);
> +                setup_max_pdx(raw_max_page);
> +            }
>          }
>  
>          if ( pfn_to_pdx((e - 1) >> PAGE_SHIFT) >= max_pdx )
> @@ -1624,6 +1636,9 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>  
>      init_frametable();
>  
> +    if ( !vm_init_done )
> +        vm_init();
> +
>      if ( !acpi_boot_table_init_done )
>          acpi_boot_table_init();
>  
> @@ -1661,12 +1676,6 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>          end_boot_allocator();
>  
>      system_state = SYS_STATE_boot;
> -    /*
> -     * No calls involving ACPI code should go between the setting of
> -     * SYS_STATE_boot and vm_init() (or else acpi_os_{,un}map_memory()
> -     * will break).
> -     */
> -    vm_init();
>  
>      bsp_stack = cpu_alloc_stack(0);
>      if ( !bsp_stack )
> diff --git a/xen/common/vmap.c b/xen/common/vmap.c
> index 4fd6b3067ec1..1340c7c6faf6 100644
> --- a/xen/common/vmap.c
> +++ b/xen/common/vmap.c
> @@ -34,9 +34,20 @@ void __init vm_init_type(enum vmap_region type, void 
> *start, void *end)
>  
>      for ( i = 0, va = (unsigned long)vm_bitmap(type); i < nr; ++i, va += 
> PAGE_SIZE )
>      {
> -        struct page_info *pg = alloc_domheap_page(NULL, 0);
> +        mfn_t mfn;
> +        int rc;
>  
> -        map_pages_to_xen(va, page_to_mfn(pg), 1, PAGE_HYPERVISOR);
> +        if ( system_state == SYS_STATE_early_boot )
> +            mfn = alloc_boot_pages(1, 1);
> +        else
> +        {
> +            struct page_info *pg = alloc_domheap_page(NULL, 0);
> +
> +            BUG_ON(!pg);
> +            mfn = page_to_mfn(pg);
> +        }
> +        rc = map_pages_to_xen(va, mfn, 1, PAGE_HYPERVISOR);
> +        BUG_ON(rc);
>          clear_page((void *)va);
>      }
>      bitmap_fill(vm_bitmap(type), vm_low[type]);
> @@ -62,7 +73,7 @@ static void *vm_alloc(unsigned int nr, unsigned int align,
>      spin_lock(&vm_lock);
>      for ( ; ; )
>      {
> -        struct page_info *pg;
> +        mfn_t mfn;
>  
>          ASSERT(vm_low[t] == vm_top[t] || !test_bit(vm_low[t], vm_bitmap(t)));
>          for ( start = vm_low[t]; start < vm_top[t]; )
> @@ -97,9 +108,16 @@ static void *vm_alloc(unsigned int nr, unsigned int align,
>          if ( vm_top[t] >= vm_end[t] )
>              return NULL;
>  
> -        pg = alloc_domheap_page(NULL, 0);
> -        if ( !pg )
> -            return NULL;
> +        if ( system_state == SYS_STATE_early_boot )
> +            mfn = alloc_boot_pages(1, 1);
> +        else
> +        {
> +            struct page_info *pg = alloc_domheap_page(NULL, 0);
> +
> +            if ( !pg )
> +                return NULL;
> +            mfn = page_to_mfn(pg);
> +        }
>  
>          spin_lock(&vm_lock);
>  
> @@ -107,7 +125,7 @@ static void *vm_alloc(unsigned int nr, unsigned int align,
>          {
>              unsigned long va = (unsigned long)vm_bitmap(t) + vm_top[t] / 8;
>  
> -            if ( !map_pages_to_xen(va, page_to_mfn(pg), 1, PAGE_HYPERVISOR) )
> +            if ( !map_pages_to_xen(va, mfn, 1, PAGE_HYPERVISOR) )
>              {
>                  clear_page((void *)va);
>                  vm_top[t] += PAGE_SIZE * 8;
> @@ -117,7 +135,10 @@ static void *vm_alloc(unsigned int nr, unsigned int 
> align,
>              }
>          }
>  
> -        free_domheap_page(pg);
> +        if ( system_state == SYS_STATE_early_boot )
> +            init_boot_pages(mfn_to_maddr(mfn), mfn_to_maddr(mfn) + 
> PAGE_SIZE);
> +        else
> +            free_domheap_page(mfn_to_page(mfn));
>  
>          if ( start >= vm_top[t] )
>          {
> -- 
> 2.38.1
> 



 


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