Re: [Xen-devel] [PATCH RFC 29/35] arm : acpi enable PSCI and hvc in acpi FADT table

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 4 Feb 2015, parth.dixit@xxxxxxxxxx wrote:
> From: Parth Dixit <parth.dixit@xxxxxxxxxx>
> 
> Enable PSCI and hvc flags in FADT table so that dom0 uses PSCI to
> boot vcpu's
> 
> Signed-off-by: Parth Dixit <parth.dixit@xxxxxxxxxx>
> ---
>  xen/arch/arm/arm64/acpi/arm-core.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/xen/arch/arm/arm64/acpi/arm-core.c 
> b/xen/arch/arm/arm64/acpi/arm-core.c
> index 6707e4c..9a26202 100644
> --- a/xen/arch/arm/arm64/acpi/arm-core.c
> +++ b/xen/arch/arm/arm64/acpi/arm-core.c
> @@ -28,6 +28,7 @@
>  #include <xen/errno.h>
>  #include <xen/stdbool.h>
>  #include <xen/cpumask.h>
> +#include <acpi/actables.h>
>  
>  #include <asm/cputype.h>
>  #include <asm/acpi.h>
> @@ -242,6 +243,19 @@ static int __init acpi_parse_fadt(struct 
> acpi_table_header *table)
>         return 0;
>  }
>  
> +static void set_psci_fadt(void)
> +{
> +    struct acpi_table_fadt *fadt=NULL;
> +    struct acpi_table_header *table=NULL;
> +    u8 checksum;
> +
> +    acpi_get_table(ACPI_SIG_FADT, 0, &table);
> +    fadt = (struct acpi_table_fadt *)table;
> +    fadt->arm_boot_flags |= ( ACPI_FADT_PSCI_COMPLIANT | 
> ACPI_FADT_PSCI_USE_HVC );

Are we actually allowed to modify the real acpi table passed by the firmware?
Could it be read-only?

If we can change it,  do we need a dsb() before the acpi_tb_checksum?


> +    checksum = acpi_tb_checksum(ACPI_CAST_PTR(u8, fadt), 
> fadt->header.length);
> +    fadt->header.checksum = (u8)( fadt->header.checksum-checksum );

and here?

> +}
>
>  int acpi_map_tables(struct domain *d)
>  {
>      int i,res;
> @@ -263,6 +277,8 @@ int acpi_map_tables(struct domain *d)
>           return res;
>      }
>  
> +    set_psci_fadt();
> +
>      for( i = 0; i < acpi_gbl_root_table_list.count; i++ )
>      {
>          addr = acpi_gbl_root_table_list.tables[i].address;
> -- 
> 1.9.1
> 

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