[v3,1/2] hw/i386/pc: pc_system_ovmf_table_find: Assert that flash was parsed

Commit Message

Dov Murik July 1, 2021, 5:27 a.m. UTC

Add assertion in pc_system_ovmf_table_find that verifies that the flash
was indeed previously parsed (looking for the OVMF table) by
pc_system_parse_ovmf_flash.

Now pc_system_ovmf_table_find distinguishes between "no one called
pc_system_parse_ovmf_flash" (which will abort due to assertion failure)
and "the flash was parsed but no OVMF table was found, or it is invalid"
(which will return false).

Suggested-by: Philippe Mathieu-Daudé <[e-mail]>
Signed-off-by: Dov Murik <[e-mail]>
Reviewed-by: Tom Lendacky <[e-mail]>
---
 hw/i386/pc_sysfw.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Philippe Mathieu-Daudé July 1, 2021, 8:54 a.m. UTC | #1

On 7/1/21 7:27 AM, Dov Murik wrote:
> Add assertion in pc_system_ovmf_table_find that verifies that the flash
> was indeed previously parsed (looking for the OVMF table) by
> pc_system_parse_ovmf_flash.
> 
> Now pc_system_ovmf_table_find distinguishes between "no one called
> pc_system_parse_ovmf_flash" (which will abort due to assertion failure)
> and "the flash was parsed but no OVMF table was found, or it is invalid"
> (which will return false).
> 
> Suggested-by: Philippe Mathieu-Daudé <[e-mail]>
> Signed-off-by: Dov Murik <[e-mail]>
> Reviewed-by: Tom Lendacky <[e-mail]>

For obvious / checkpatch fixes you can keep the tags ;)

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>

> ---
>  hw/i386/pc_sysfw.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Dov Murik July 1, 2021, 9:28 a.m. UTC | #2

On 01/07/2021 11:54, Philippe Mathieu-Daudé wrote:
> On 7/1/21 7:27 AM, Dov Murik wrote:
>> Add assertion in pc_system_ovmf_table_find that verifies that the flash
>> was indeed previously parsed (looking for the OVMF table) by
>> pc_system_parse_ovmf_flash.
>>
>> Now pc_system_ovmf_table_find distinguishes between "no one called
>> pc_system_parse_ovmf_flash" (which will abort due to assertion failure)
>> and "the flash was parsed but no OVMF table was found, or it is invalid"
>> (which will return false).
>>
>> Suggested-by: Philippe Mathieu-Daudé <[e-mail]>
>> Signed-off-by: Dov Murik <[e-mail]>
>> Reviewed-by: Tom Lendacky <[e-mail]>
> 
> For obvious / checkpatch fixes you can keep the tags ;)
> 
> Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
> 

Thanks Phil.

-Dov

Patch

diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 6ce37a2b05..e353f2a4e9 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -126,6 +126,7 @@  void pc_system_flash_cleanup_unused(PCMachineState *pcms)
 
 #define OVMF_TABLE_FOOTER_GUID "96b582de-1fb2-45f7-baea-a366c55a082d"
 
+static bool ovmf_flash_parsed;
 static uint8_t *ovmf_table;
 static int ovmf_table_len;
 
@@ -136,10 +137,12 @@  static void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size)
     int tot_len;
 
     /* should only be called once */
-    if (ovmf_table) {
+    if (ovmf_flash_parsed) {
         return;
     }
 
+    ovmf_flash_parsed = true;
+
     if (flash_size < TARGET_PAGE_SIZE) {
         return;
     }
@@ -183,6 +186,8 @@  bool pc_system_ovmf_table_find(const char *entry, uint8_t **data,
     int tot_len = ovmf_table_len;
     QemuUUID entry_guid;
 
+    assert(ovmf_flash_parsed);
+
     if (qemu_uuid_parse(entry, &entry_guid) < 0) {
         return false;
     }