Re: [Xen-devel] [PATCH v6 18/22] arm/acpi: Permit MMIO access of Xen unused devices for Dom0

[Julien Grall <julien.grall@xxxxxxx>]

Hi Shannon,

On 17/03/16 09:41, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> Firstly it permits full MMIO capabilities for Dom0. Then deny MMIO
> access of Xen used devices, such as UART, GIC, SMMU. Currently, it only
> denies the MMIO access of UART and GIC regions. For other Xen used
> devices it could be added later when they are supported.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

> ---
>   xen/arch/arm/domain_build.c | 36 ++++++++++++++++++++++++++++++++++++
>   1 file changed, 36 insertions(+)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 1e5ee0e..a4abf28 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -1359,6 +1359,38 @@ static int prepare_dtb(struct domain *d, struct 
> kernel_info *kinfo)
>   #ifdef CONFIG_ACPI
>   #define ACPI_DOM0_FDT_MIN_SIZE 4096
>
> +static int acpi_iomem_deny_access(struct domain *d)
> +{
> +    acpi_status status;
> +    struct acpi_table_spcr *spcr = NULL;
> +    unsigned long gfn;
> +    int rc;
> +
> +    /* Firstly permit full MMIO capabilities. */
> +    rc = iomem_permit_access(d, 0UL, ~0UL);
> +    if ( rc )
> +        return rc;
> +
> +    /* TODO: Deny MMIO access for SMMU, GIC ITS */
> +    status = acpi_get_table(ACPI_SIG_SPCR, 0,
> +                            (struct acpi_table_header **)&spcr);
> +
> +    if ( ACPI_FAILURE(status) )
> +    {
> +        printk("Failed to get SPCR table\n");
> +        return -EINVAL;
> +    }
> +
> +    gfn = spcr->serial_port.address >> PAGE_SHIFT;
> +    /* Deny MMIO access for UART */
> +    rc = iomem_deny_access(d, gfn, gfn + 1);
> +    if ( rc )
> +        return rc;
> +
> +    /* Deny MMIO access for GIC regions */
> +    return gic_iomem_deny_access(d);
> +}
> +
>   static int acpi_permit_spi_access(struct domain *d)
>   {
>       int i, res;
> @@ -1880,6 +1912,10 @@ static int prepare_acpi(struct domain *d, struct 
> kernel_info *kinfo)
>       if ( rc != 0 )
>           return rc;
>
> +    rc = acpi_iomem_deny_access(d);
> +    if ( rc != 0 )
> +        return rc;
> +
>       return 0;
>   }
>   #else
Regards,

--
Julien Grall

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