Re: [Xen-devel] [RFC QEMU PATCH v4 05/10] xen-hvm: initialize fw_cfg interface

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Thu, Dec 07, 2017 at 06:18:07PM +0800, Haozhong Zhang wrote:
> Xen is going to reuse QEMU to build ACPI of some devices (e.g., NFIT
> and SSDT for NVDIMM) for HVM domains. The existing QEMU ACPI build
> code requires a fw_cfg interface which will also be used to pass QEMU
> built ACPI to Xen. Therefore, we need to initialize fw_cfg when any
> ACPI is going to be built by QEMU.
> 
> Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Anthony Perard <anthony.perard@xxxxxxxxxx>
> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Richard Henderson <rth@xxxxxxxxxxx>
> Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx>
> ---
>  hw/i386/xen/xen-hvm.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
> index fe01b7a025..4b29f4052b 100644
> --- a/hw/i386/xen/xen-hvm.c
> +++ b/hw/i386/xen/xen-hvm.c
> @@ -14,6 +14,7 @@
>  #include "hw/pci/pci.h"
>  #include "hw/i386/pc.h"
>  #include "hw/i386/apic-msidef.h"
> +#include "hw/loader.h"
>  #include "hw/xen/xen_common.h"
>  #include "hw/xen/xen_backend.h"
>  #include "qmp-commands.h"
> @@ -1234,6 +1235,14 @@ static void xen_wakeup_notifier(Notifier *notifier, 
> void *data)
>      xc_set_hvm_param(xen_xc, xen_domid, HVM_PARAM_ACPI_S_STATE, 0);
>  }
>  
> +static void xen_fw_cfg_init(PCMachineState *pcms)
> +{

The fw_cfg interface might already be initialized, it is used for
"direct kernel boot" on hvm. It is initialized in xen_load_linux().

> +    FWCfgState *fw_cfg = fw_cfg_init_io(FW_CFG_IO_BASE);
> +
> +    rom_set_fw(fw_cfg);
> +    pcms->fw_cfg = fw_cfg;
> +}
> +
>  void xen_hvm_init(PCMachineState *pcms, MemoryRegion **ram_memory)
>  {
>      int i, rc;
> @@ -1384,6 +1393,9 @@ void xen_hvm_init(PCMachineState *pcms, MemoryRegion 
> **ram_memory)
>  
>      /* Disable ACPI build because Xen handles it */
>      pcms->acpi_build_enabled = false;
> +    if (pcms->acpi_build_enabled) {
> +        xen_fw_cfg_init(pcms);
> +    }
>  
>      return;
>  
> -- 
> 2.15.1
> 

-- 
Anthony PERARD

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