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Re: [PATCH v2] hw/isa/piix4: Migrate Reset Control Register
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH v2] hw/isa/piix4: Migrate Reset Control Register |
Date: |
Wed, 24 Mar 2021 21:00:33 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 |
On 3/24/21 8:40 PM, Dr. David Alan Gilbert wrote:
> * Philippe Mathieu-Daudé (f4bug@amsat.org) wrote:
>> When adding the Reset register in commit 5790b757cfb we
>> forgot to migrate it.
>>
>> While it is possible a VM using the PIIX4 is migrated just
>> after requesting a system shutdown, it is very unlikely.
>> However when restoring a migrated VM, we might have the
>> RCR bit #4 set on the stack and when the VM resume it
>> directly shutdowns.
>>
>> Add a post_load() migration handler and set the default
>> RCR value to 0 for earlier versions, assuming the VM was
>> not going to shutdown before migration.
>>
>> Fixes: 5790b757cfb ("piix4: Add the Reset Control Register")
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>> v2: Add piix4_ide_post_load() and describe
>> ---
>> hw/isa/piix4.c | 15 ++++++++++++++-
>> 1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/isa/piix4.c b/hw/isa/piix4.c
>> index a50d97834c7..e7bce0e590c 100644
>> --- a/hw/isa/piix4.c
>> +++ b/hw/isa/piix4.c
>> @@ -93,12 +93,25 @@ static void piix4_isa_reset(DeviceState *dev)
>> pci_conf[0xae] = 0x00;
>> }
>>
>> +static int piix4_ide_post_load(void *opaque, int version_id)
>> +{
>> + PIIX4State *s = opaque;
>> +
>> + if (version_id == 2) {
>> + s->rcr = 0;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static const VMStateDescription vmstate_piix4 = {
>> .name = "PIIX4",
>> - .version_id = 2,
>> + .version_id = 3,
>> .minimum_version_id = 2,
>> + .post_load = piix4_ide_post_load,
>> .fields = (VMStateField[]) {
>> VMSTATE_PCI_DEVICE(dev, PIIX4State),
>> + VMSTATE_UINT8(rcr, PIIX4State),
>
> I don't think that looks right any more; you'd need to make that a
> VMSTATE_UINT8_V(rcr, PIIX4State, 3),
>
> I think, otherwise when you loaded a v2 it would still try
> and read the rcr byte.
Ah now I guess I understood.
Thanks!