Re: [Xen-devel] [PATCH v3 40/62] arm/acpi: Estimate memory required for acpi/efi tables

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 31 Dec 2015, Shannon Zhao wrote:
> On 2015/11/27 0:39, Stefano Stabellini wrote:
> > On Tue, 17 Nov 2015, shannon.zhao@xxxxxxxxxx wrote:
> >> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> >>
> >> Estimate the memory required for loading acpi/efi tables in Dom0. Alloc
> >> the pages to store the new created EFI and ACPI tables and free these
> >> pages when destroying domain.
> > 
> > Could you please explain what you are page aligning exactly and why?
> > 
> 
> At least it should be 64bit aligned of the table start address. If not,
> guest will throw out an alignment fault.
> 
> ACPI: Using GIC for interrupt routing
> Unhandled fault: alignment fault (0x96000021) at 0xffffff800006c19c
> Internal error: : 96000021 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.3.0+ #551
> Hardware name: (null) (DT)
> task: ffffffc008870000 ti: ffffffc00884c000 task.ti: ffffffc00884c000
> PC is at acpi_get_phys_id+0x264/0x290
> LR is at acpi_get_phys_id+0x178/0x290

OK, but between page alignment and 64-bit alignment there is a very big
difference.


> > 
> >>
> >> Signed-off-by: Parth Dixit <parth.dixit@xxxxxxxxxx>
> >> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> >> ---
> >>  xen/arch/arm/domain.c       |  4 +++
> >>  xen/arch/arm/domain_build.c | 80 
> >> ++++++++++++++++++++++++++++++++++++++++++++-
> >>  xen/common/efi/boot.c       | 21 ++++++++++++
> >>  xen/include/asm-arm/setup.h |  2 ++
> >>  4 files changed, 106 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> >> index 880d0a6..10c58c4 100644
> >> --- a/xen/arch/arm/domain.c
> >> +++ b/xen/arch/arm/domain.c
> >> @@ -638,6 +638,10 @@ void arch_domain_destroy(struct domain *d)
> >>      domain_vgic_free(d);
> >>      domain_vuart_free(d);
> >>      free_xenheap_page(d->shared_info);
> >> +#ifdef CONFIG_ACPI
> >> +    free_xenheap_pages(d->arch.efi_acpi_table,
> >> +                       get_order_from_bytes(d->arch.efi_acpi_len));
> >> +#endif
> >>  }
> >>  
> >>  void arch_domain_shutdown(struct domain *d)
> >> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> >> index 0c3441a..b5ed44c 100644
> >> --- a/xen/arch/arm/domain_build.c
> >> +++ b/xen/arch/arm/domain_build.c
> >> @@ -12,6 +12,8 @@
> >>  #include <xen/libfdt/libfdt.h>
> >>  #include <xen/guest_access.h>
> >>  #include <xen/iocap.h>
> >> +#include <xen/acpi.h>
> >> +#include <acpi/actables.h>
> >>  #include <asm/device.h>
> >>  #include <asm/setup.h>
> >>  #include <asm/platform.h>
> >> @@ -1354,6 +1356,78 @@ static int prepare_dtb(struct domain *d, struct 
> >> kernel_info *kinfo)
> >>      return -EINVAL;
> >>  }
> >>  
> >> +#ifdef CONFIG_ACPI
> >> +static int estimate_acpi_efi_size(struct domain *d, struct kernel_info 
> >> *kinfo)
> >> +{
> >> +    u64 efi_size, acpi_size = 0, addr;
> >> +    u32 madt_size;
> >> +    struct acpi_table_rsdp *rsdp_tbl;
> >> +    struct acpi_table_header *table = NULL;
> >> +
> >> +    efi_size = estimate_efi_size(kinfo->mem.nr_banks);
> >> +
> >> +    acpi_size += PAGE_ALIGN(sizeof(struct acpi_table_fadt));
> >> +    acpi_size += PAGE_ALIGN(sizeof(struct acpi_table_stao));
> >> +
> >> +    madt_size = sizeof(struct acpi_table_madt)
> >> +                + sizeof(struct acpi_madt_generic_interrupt) * 
> >> d->max_vcpus
> >> +                + sizeof(struct acpi_madt_generic_distributor);
> >> +    if ( d->arch.vgic.version == GIC_V3 )
> >> +        madt_size += sizeof(struct acpi_madt_generic_redistributor)
> >> +                     * d->arch.vgic.nr_regions;
> >> +    acpi_size += PAGE_ALIGN(madt_size);
> > 
> > are the MADT and FADT tables guaranteed to be on separate pages or is it
> > just an estimate?
> > 
> > 
> >> +    addr = acpi_os_get_root_pointer();
> >> +    if ( !addr )
> >> +    {
> >> +        printk("Unable to get acpi root pointer\n");
> >> +        return -EINVAL;
> >> +    }
> >> +    rsdp_tbl = acpi_os_map_memory(addr, sizeof(struct acpi_table_rsdp));
> >> +    table = acpi_os_map_memory(rsdp_tbl->xsdt_physical_address,
> >> +                               sizeof(struct acpi_table_header));
> >> +    acpi_size += PAGE_ALIGN(table->length + sizeof(u64));
> >> +    acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
> >> +    acpi_os_unmap_memory(rsdp_tbl, sizeof(struct acpi_table_rsdp));
> >> +
> >> +    acpi_size += PAGE_ALIGN(sizeof(struct acpi_table_rsdp));
> >> +    d->arch.efi_acpi_len = PAGE_ALIGN(efi_size) + PAGE_ALIGN(acpi_size);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +static int prepare_acpi(struct domain *d, struct kernel_info *kinfo)
> >> +{
> >> +    int rc = 0;
> >> +    int order;
> >> +
> >> +    rc = estimate_acpi_efi_size(d, kinfo);
> >> +    if ( rc != 0 )
> >> +        return rc;
> >> +
> >> +    order = get_order_from_bytes(d->arch.efi_acpi_len);
> >> +    d->arch.efi_acpi_table = alloc_xenheap_pages(order, 0);
> >> +    if ( d->arch.efi_acpi_table == NULL )
> >> +    {
> >> +        printk("unable to allocate memory!\n");
> >> +        return -1;
> > 
> > ENOMEM
> > 
> > 
> >> +    }
> >> +    memset(d->arch.efi_acpi_table, 0, d->arch.efi_acpi_len);
> >> +
> >> +    /* For ACPI, Dom0 doesn't use kinfo->gnttab_start to get the grant 
> >> table
> >> +     * region. So we use it as the ACPI table mapped address. */
> >> +    d->arch.efi_acpi_gpa = kinfo->gnttab_start;
> >> +
> >> +    return 0;
> >> +}
> >> +#else
> >> +static int prepare_acpi(struct domain *d, struct kernel_info *kinfo)
> >> +{
> >> +    /* Only booting with ACPI will hit here */
> >> +    BUG_ON(1);
> >> +    return -EINVAL;
> >> +}
> >> +#endif
> >>  static void dtb_load(struct kernel_info *kinfo)
> >>  {
> >>      void * __user dtb_virt = (void * __user)(register_t)kinfo->dtb_paddr;
> >> @@ -1540,7 +1614,11 @@ int construct_dom0(struct domain *d)
> >>      allocate_memory(d, &kinfo);
> >>      find_gnttab_region(d, &kinfo);
> >>  
> >> -    rc = prepare_dtb(d, &kinfo);
> >> +    if ( acpi_disabled )
> >> +        rc = prepare_dtb(d, &kinfo);
> >> +    else
> >> +        rc = prepare_acpi(d, &kinfo);
> >> +
> >>      if ( rc < 0 )
> >>          return rc;
> >>  
> >> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> >> index 53c7452..78d8ae9 100644
> >> --- a/xen/common/efi/boot.c
> >> +++ b/xen/common/efi/boot.c
> >> @@ -13,6 +13,7 @@
> >>  #include <xen/multiboot.h>
> >>  #include <xen/pci_regs.h>
> >>  #include <xen/pfn.h>
> >> +#include <asm/acpi.h>
> >>  #if EFI_PAGE_SIZE != PAGE_SIZE
> >>  # error Cannot use xen/pfn.h here!
> >>  #endif
> >> @@ -1171,6 +1172,26 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE 
> >> *SystemTable)
> >>      for( ; ; ); /* not reached */
> >>  }
> >>  
> >> +#ifdef CONFIG_ACPI
> >> +/* Constant to indicate "Xen" in unicode u16 format */
> >> +static const u16 XEN_EFI_FW_VENDOR[] ={0x0058,0x0065,0x006E,0x0000};
> >> +
> >> +int __init estimate_efi_size(int mem_nr_banks)
> >> +{
> >> +    int size;
> >> +    int est_size = sizeof(EFI_SYSTEM_TABLE);
> >> +    int ect_size = sizeof(EFI_CONFIGURATION_TABLE);
> >> +    int emd_size = sizeof(EFI_MEMORY_DESCRIPTOR);
> >> +    int fw_vendor_size = sizeof(XEN_EFI_FW_VENDOR);
> >> +
> >> +    size = PAGE_ALIGN(est_size + ect_size + fw_vendor_size)
> >> +           + PAGE_ALIGN(emd_size *
> >> +                        (mem_nr_banks + acpi_mem.nr_banks + TBL_MMAX));
> > 
> > Why are they on two separate pages? Is it mandated by the EFI spec?
> > Why are you adding TBL_MMAX to the multiplicand here?
> > 
> > I don't like that we are passing mem_nr_banks as argument but we are
> > accessing acpi_mem.nr_banks from the global variable. I would prefer if
> > they were both passed as arguments.
> > 
> > 
> >> +    return size;
> >> +}
> >> +#endif
> >> +
> >>  #ifndef CONFIG_ARM /* TODO - runtime service support */
> >>  
> >>  static bool_t __initdata efi_rs_enable = 1;
> >> diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h
> >> index 30ac53b..b759813 100644
> >> --- a/xen/include/asm-arm/setup.h
> >> +++ b/xen/include/asm-arm/setup.h
> >> @@ -51,6 +51,8 @@ void arch_init_memory(void);
> >>  
> >>  void copy_from_paddr(void *dst, paddr_t paddr, unsigned long len);
> >>  
> >> +int estimate_efi_size(int mem_nr_banks);
> >> +
> >>  int construct_dom0(struct domain *d);
> >>  
> >>  void discard_initial_modules(void);
> >> -- 
> >> 2.1.0
> >>
> > 
> > .
> > 
> 
> -- 
> Shannon
> 

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