On 8/5/24 10:17, Bernhard Beschow wrote:
Am 30. April 2024 15:39:21 UTC schrieb "Philippe Mathieu-Daudé"
<phi...@linaro.org>:
On 30/4/24 17:06, Bernhard Beschow wrote:
In the -bios case the "isa-bios" memory region is an alias to the BIOS mapped
to the top of the 4G memory boundary. Do the same in the -pflash case, but only
for new machine versions for migration compatibility. This establishes common
behavior and makes pflash commands work in the "isa-bios" region which some
real-world legacy bioses rely on.
Can you amend a diff of 'info mtree' here to see how the layout changes?
Will do.
Right now I have to manually sort the output to get a minimal diff. Is there a
way to get a stable ordering of the memory regions? How would one fix that if
this is currently impossible? With stable orderings we could have automated
memory map tests which had been handy in the past.
It is stable until the guest plays with it, so it depends at which
point in guest execution time you stop your VM to dump the mem tree.
Note that in the sev_enabled() case, the "isa-bios" memory region in the -pflash
case will now also point to encrypted memory, just like it already does in the
-bios case.
Signed-off-by: Bernhard Beschow <shen...@gmail.com>
---
include/hw/i386/pc.h | 1 +
hw/i386/pc.c | 1 +
hw/i386/pc_piix.c | 3 +++
hw/i386/pc_q35.c | 2 ++
hw/i386/pc_sysfw.c | 8 +++++++-
5 files changed, 14 insertions(+), 1 deletion(-)
I'm still not convinced we need a migration back compat for this...
A copy behaves different than an alias, thus there is a behavioral change.
Whether it really matters in practice for the kind of guests we care about I
can't tell. Therefore I'd keep the compat machinery.
Yeah I know MST asked that, I'm not against, I'm just not convinced
(in particular because we'll need to maintain these few lines for
6 years).
Best regards,
Bernhard
diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 82d37cb376..ac88ad4eb9 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -135,6 +135,7 @@ static void pc_system_flash_map(PCMachineState *pcms,
MemoryRegion *rom_memory)
{
X86MachineState *x86ms = X86_MACHINE(pcms);
+ PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
hwaddr total_size = 0;
int i;
BlockBackend *blk;
@@ -184,7 +185,12 @@ static void pc_system_flash_map(PCMachineState *pcms,
if (i == 0) {
flash_mem = pflash_cfi01_get_memory(system_flash);
- pc_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem);
+ if (pcmc->isa_bios_alias) {
+ x86_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem,
+ true);
+ } else {
+ pc_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem);
+ }
/* Encrypt the pflash boot ROM */
if (sev_enabled()) {
