Re: [PATCH 04/16] hw/uefi: add var-service-guid.c

[Laszlo Ersek <lersek@redhat.com>]

On 11/15/23 16:12, Gerd Hoffmann wrote:
> Add variables for a bunch of GUIDs we will need.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/uefi/var-service-guid.c | 61 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
>  create mode 100644 hw/uefi/var-service-guid.c
> 
> diff --git a/hw/uefi/var-service-guid.c b/hw/uefi/var-service-guid.c
> new file mode 100644
> index 000000000000..afdc15c4e7e6
> --- /dev/null
> +++ b/hw/uefi/var-service-guid.c
> @@ -0,0 +1,61 @@
> +/*
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * uefi vars device - GUIDs
> + */
> +
> +#include "qemu/osdep.h"
> +#include "sysemu/dma.h"
> +
> +#include "hw/uefi/var-service.h"
> +
> +/* variable namespaces */
> +
> +QemuUUID EfiGlobalVariable = {
> +    .data = UUID_LE(0x8be4df61, 0x93ca, 0x11d2, 0xaa, 0x0d,
> +                    0x00, 0xe0, 0x98, 0x03, 0x2b, 0x8c)
> +};

(1) should have asked under patch#3:

can we constify these?

> +
> +QemuUUID EfiImageSecurityDatabase = {
> +    .data = UUID_LE(0xd719b2cb, 0x3d3a, 0x4596, 0xa3, 0xbc,
> +                    0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f)
> +};
> +
> +QemuUUID EfiCustomModeEnable = {
> +    .data = UUID_LE(0xc076ec0c, 0x7028, 0x4399, 0xa0, 0x72,
> +                    0x71, 0xee, 0x5c, 0x44, 0x8b, 0x9f)
> +};
> +
> +QemuUUID EfiSecureBootEnableDisable = {
> +    .data = UUID_LE(0xf0a30bc7, 0xaf08, 0x4556, 0x99, 0xc4,
> +                    0x0, 0x10, 0x9, 0xc9, 0x3a, 0x44)
> +};
> +
> +/* protocols */
> +
> +QemuUUID EfiSmmVariableProtocolGuid = {
> +    .data = UUID_LE(0xed32d533, 0x99e6, 0x4209, 0x9c, 0xc0,
> +                    0x2d, 0x72, 0xcd, 0xd9, 0x98, 0xa7)
> +};
> +
> +QemuUUID VarCheckPolicyLibMmiHandlerGuid = {
> +    .data = UUID_LE(0xda1b0d11, 0xd1a7, 0x46c4, 0x9d, 0xc9,
> +                    0xf3, 0x71, 0x48, 0x75, 0xc6, 0xeb)
> +};

This isn't really a  protocol, but a GUID for "mm_header.guid".

gEfiSmmVariableProtocolGuid is a bit messy in edk2 because (IIUC) it is
used for *three* purposes:

(a) it's an actual SMM protocol GUID (MmVariableServiceInitialize() --
MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c),

(b) it's used as "mm_header.guid" (see the MmiHandlerRegister call in
the same location), i.e. basically an SMI "upcall" identifier

(c) it's used as a NULL interface DXE protocol GUID for notification
purposes (VariableNotifySmmReady() --
MdeModulePkg/Universal/Variable/RuntimeDxe/VariableTraditionalMm.c).

So calling gEfiSmmVariableProtocolGuid a "protocol" in this header file
is relatively justified. But calling "VarCheckPolicyLibMmiHandlerGuid" a
protocol doesn't seem justified, because (I think) it only qualifies for
usage (b).

> +
> +/* events */

More precisely, this would be "event groups"; but peaking ahead to the
next patch, I think all five of these GUIDs (protocols + events) are
just "mm_header.guid" values.

So here's what I propose:

(2) replace

  /* protocols */

with

  /* mm_header.guid values that the guest DXE/BDS phases use for
   * sending requests to management mode
   */

and

(3) replace

  /* events */

with

  /* mm_header.guid values that the guest DXE/BDS phases use for
   * reporting event groups being signaled to management mode
   */

> +
> +QemuUUID EfiEndOfDxeEventGroupGuid = {
> +    .data = UUID_LE(0x02CE967A, 0xDD7E, 0x4FFC, 0x9E, 0xE7,
> +                    0x81, 0x0C, 0xF0, 0x47, 0x08, 0x80)
> +};

(4) I suggest consistently using either the lowercase hex characters
[a-f] or the uppercase ones [A-F] across all GUID constants in this header.


> +
> +QemuUUID EfiEventReadyToBootGuid = {
> +    .data = UUID_LE(0x7CE88FB3, 0x4BD7, 0x4679, 0x87, 0xA8,
> +                    0xA8, 0xD8, 0xDE, 0xE5, 0x0D, 0x2B)
> +};
> +
> +QemuUUID EfiEventExitBootServicesGuid = {
> +    .data = UUID_LE(0x27ABF055, 0xB1B8, 0x4C26, 0x80, 0x48,
> +                    0x74, 0x8F, 0x37, 0xBA, 0xA2, 0xDF)
> +};

I've made an effort to verify the constants themselves; they look good.

Thanks
Laszlo