Re: [PATCH v3] xen/x86/pvh: handle ACPI RSDT table in PVH Dom0 build

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

Ping?

I think this is a useful change, could we please have a new version
with the proposed adjustments?

Thanks, Roger.

On Wed, Apr 24, 2024 at 03:18:26PM -0400, Daniel P. Smith wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> 
> Xen always generates as XSDT table even if the firmware provided an RSDT 
> table.
> Copy the RSDT header from the firmware table, adjusting the signature, for the
> XSDT table when not provided by the firmware.
> 
> Fixes: 1d74282c455f ('x86: setup PVHv2 Dom0 ACPI tables')
> Suggested-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> ---
> 
> This patch is used for development and testing of hyperlaunch using the QEMU
> emulator. After dicussiong with Stefano, he was okay with me addressing Jan's
> comment regarding the table signature and reposting for acceptance.
> 
> Changes in v3:
> - ensure the constructed XSDT table always has the correct signature
> 
> ---
>  xen/arch/x86/hvm/dom0_build.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
> index ac71d43a6b3f..781aac00fe72 100644
> --- a/xen/arch/x86/hvm/dom0_build.c
> +++ b/xen/arch/x86/hvm/dom0_build.c
> @@ -1077,7 +1077,16 @@ static int __init pvh_setup_acpi_xsdt(struct domain 
> *d, paddr_t madt_addr,
>          rc = -EINVAL;
>          goto out;
>      }
> -    xsdt_paddr = rsdp->xsdt_physical_address;
> +    /*
> +     * Note the header is the same for both RSDT and XSDT, so it's fine to
> +     * copy the native RSDT header to the Xen crafted XSDT if no native
> +     * XSDT is available.
> +     */
> +    if ( rsdp->revision > 1 && rsdp->xsdt_physical_address )
> +        xsdt_paddr = rsdp->xsdt_physical_address;
> +    else
> +        xsdt_paddr = rsdp->rsdt_physical_address;
> +
>      acpi_os_unmap_memory(rsdp, sizeof(*rsdp));
>      table = acpi_os_map_memory(xsdt_paddr, sizeof(*table));
>      if ( !table )
> @@ -1089,6 +1098,9 @@ static int __init pvh_setup_acpi_xsdt(struct domain *d, 
> paddr_t madt_addr,
>      xsdt->header = *table;
>      acpi_os_unmap_memory(table, sizeof(*table));
>  
> +    /* In case the header is an RSDT copy, blindly ensure it has an XSDT sig 
> */
> +    xsdt->header.signature[0] = 'X';
> +
>      /* Add the custom MADT. */
>      xsdt->table_offset_entry[0] = madt_addr;
>  
> -- 
> 2.30.2
>