* Philippe Mathieu-Daudé (phi...@redhat.com) wrote: > In the "Read Array Flowchart" the command has a value of 0xFF. > > In the document [*] the "Read Array Flowchart", the READ_ARRAY > command has a value of 0xff. > > Use the correct value in the pflash model. > > There is no change of behavior in the guest, because: > - when the guest were sending 0xFF, the reset_flash label > was setting the command value as 0x00 > - 0x00 was used internally for READ_ARRAY > > To keep migration behaving correctly, we have to increase > the VMState version. When migrating from an older version, > we use the correct command value.
The problem is that incrementing the version will break backwards compatibility; so you won't be able to migrate this back to an older QEMU version; so for example a q35/uefi with this won't be able to migrate backwards to a 4.0.0 or older qemu. So instead of bumping the version_id you probably need to wire the behaviour to a machine type and then on your new type wire a subsection containing a flag; the reception of that subsection tells you to use the new/correct semantics. Dave > [*] "Common Flash Interface (CFI) and Command Sets" > (Intel Application Note 646) > Appendix B "Basic Command Set" > > Reviewed-by: John Snow <js...@redhat.com> > Reviewed-by: Alistair Francis <alistair.fran...@wdc.com> > Regression-tested-by: Laszlo Ersek <ler...@redhat.com> > Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> > --- > v3: Handle migrating the 'cmd' field. > > Since Laszlo stated he did not test migration [*], I'm keeping his > test tag, because the change with v2 has no impact in the tests > he ran. > > Likewise I'm keeping John and Alistair tags, but I'd like an extra > review for the migration change, thanks! > > [*] https://lists.gnu.org/archive/html/qemu-devel/2019-07/msg00679.html > --- > hw/block/pflash_cfi01.c | 23 +++++++++++++---------- > 1 file changed, 13 insertions(+), 10 deletions(-) > > diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c > index 9e34fd4e82..58cbef0588 100644 > --- a/hw/block/pflash_cfi01.c > +++ b/hw/block/pflash_cfi01.c > @@ -100,7 +100,7 @@ static int pflash_post_load(void *opaque, int version_id); > > static const VMStateDescription vmstate_pflash = { > .name = "pflash_cfi01", > - .version_id = 1, > + .version_id = 2, > .minimum_version_id = 1, > .post_load = pflash_post_load, > .fields = (VMStateField[]) { > @@ -277,10 +277,9 @@ static uint32_t pflash_read(PFlashCFI01 *pfl, hwaddr > offset, > /* This should never happen : reset state & treat it as a read */ > DPRINTF("%s: unknown command state: %x\n", __func__, pfl->cmd); > pfl->wcycle = 0; > - pfl->cmd = 0; > + pfl->cmd = 0xff; > /* fall through to read code */ > - case 0x00: > - /* Flash area read */ > + case 0xff: /* Read Array */ > ret = pflash_data_read(pfl, offset, width, be); > break; > case 0x10: /* Single byte program */ > @@ -448,8 +447,6 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset, > case 0: > /* read mode */ > switch (cmd) { > - case 0x00: /* ??? */ > - goto reset_flash; > case 0x10: /* Single Byte Program */ > case 0x40: /* Single Byte Program */ > DPRINTF("%s: Single Byte Program\n", __func__); > @@ -526,7 +523,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset, > if (cmd == 0xd0) { /* confirm */ > pfl->wcycle = 0; > pfl->status |= 0x80; > - } else if (cmd == 0xff) { /* read array mode */ > + } else if (cmd == 0xff) { /* Read Array */ > goto reset_flash; > } else > goto error_flash; > @@ -553,7 +550,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset, > } else if (cmd == 0x01) { > pfl->wcycle = 0; > pfl->status |= 0x80; > - } else if (cmd == 0xff) { > + } else if (cmd == 0xff) { /* read array mode */ > goto reset_flash; > } else { > DPRINTF("%s: Unknown (un)locking command\n", __func__); > @@ -645,7 +642,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset, > trace_pflash_reset(); > memory_region_rom_device_set_romd(&pfl->mem, true); > pfl->wcycle = 0; > - pfl->cmd = 0; > + pfl->cmd = 0xff; > } > > > @@ -761,7 +758,7 @@ static void pflash_cfi01_realize(DeviceState *dev, Error > **errp) > } > > pfl->wcycle = 0; > - pfl->cmd = 0; > + pfl->cmd = 0xff; > pfl->status = 0; > /* Hardcoded CFI table */ > /* Standard "QRY" string */ > @@ -1001,5 +998,11 @@ static int pflash_post_load(void *opaque, int > version_id) > pfl->vmstate = qemu_add_vm_change_state_handler(postload_update_cb, > pfl); > } > + if (version_id < 2) { > + /* v1 used incorrect value of 0x00 for the READ_ARRAY command. */ > + if (pfl->cmd == 0x00) { > + pfl->cmd = 0xff; > + } > + } > return 0; > } > -- > 2.20.1 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK