Re: [PULL 1/2] tpm: CRB: Use ram_device for "tpm-crb-cmd" region

[Eric Auger <eric.auger@redhat.com>]

Hi Igor,
On 2/4/22 1:08 PM, Igor Mammedov wrote:
> On Thu, 03 Feb 2022 15:35:35 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
>
>> From: Eric Auger <eric.auger@redhat.com>
>>
>> Representing the CRB cmd/response buffer as a standard
>> RAM region causes some trouble when the device is used
>> with VFIO. Indeed VFIO attempts to DMA_MAP this region
>> as usual RAM but this latter does not have a valid page
>> size alignment causing such an error report:
>> "vfio_listener_region_add received unaligned region".
>> To allow VFIO to detect that failing dma mapping
>> this region is not an issue, let's use a ram_device
>> memory region type instead.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> Tested-by: Stefan Berger <stefanb@linux.ibm.com>
>> Acked-by: Stefan Berger <stefanb@linux.ibm.com>
>> [PMD: Keep tpm_crb.c in meson's softmmu_ss]
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> Link: https://lore.kernel.org/r/20220120001242.230082-2-f4bug@amsat.org
>> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
>> ---
>>  hw/tpm/tpm_crb.c |   22 ++++++++++++++++++++--
>>  1 file changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/tpm/tpm_crb.c b/hw/tpm/tpm_crb.c
>> index 58ebd1469c35..be0884ea6031 100644
>> --- a/hw/tpm/tpm_crb.c
>> +++ b/hw/tpm/tpm_crb.c
>> @@ -25,6 +25,7 @@
>>  #include "sysemu/tpm_backend.h"
>>  #include "sysemu/tpm_util.h"
>>  #include "sysemu/reset.h"
>> +#include "exec/cpu-common.h"
>>  #include "tpm_prop.h"
>>  #include "tpm_ppi.h"
>>  #include "trace.h"
>> @@ -43,6 +44,7 @@ struct CRBState {
>>  
>>      bool ppi_enabled;
>>      TPMPPI ppi;
>> +    uint8_t *crb_cmd_buf;
>>  };
>>  typedef struct CRBState CRBState;
>>  
>> @@ -291,10 +293,14 @@ static void tpm_crb_realize(DeviceState *dev, Error **errp)
>>          return;
>>      }
>>  
>> +    s->crb_cmd_buf = qemu_memalign(qemu_real_host_page_size,
>> +                                HOST_PAGE_ALIGN(CRB_CTRL_CMD_SIZE));
>> +
>>      memory_region_init_io(&s->mmio, OBJECT(s), &tpm_crb_memory_ops, s,
>>          "tpm-crb-mmio", sizeof(s->regs));
>> -    memory_region_init_ram(&s->cmdmem, OBJECT(s),
>> -        "tpm-crb-cmd", CRB_CTRL_CMD_SIZE, errp);
>> +    memory_region_init_ram_device_ptr(&s->cmdmem, OBJECT(s), "tpm-crb-cmd",
>> +                                      CRB_CTRL_CMD_SIZE, s->crb_cmd_buf);
>> +    vmstate_register_ram(&s->cmdmem, DEVICE(s));
> Does it need a compat knob for the case of migrating to older QEMU/machine type,
> not to end-up with target aborting migration when it sees unknown section.
Hum I did not think about this. I need to double check.

Thank you for the review.

Eric
>
>
>>      memory_region_add_subregion(get_system_memory(),
>>          TPM_CRB_ADDR_BASE, &s->mmio);
>> @@ -309,12 +315,24 @@ static void tpm_crb_realize(DeviceState *dev, Error **errp)
>>      qemu_register_reset(tpm_crb_reset, dev);
>>  }
>>  
>> +static void tpm_crb_unrealize(DeviceState *dev)
>> +{
>> +    CRBState *s = CRB(dev);
>> +
> likewise, should vmstate be unregistered here, before freeing
> actually happens?
>
>> +    qemu_vfree(s->crb_cmd_buf);
>> +
>> +    if (s->ppi_enabled) {
>> +        qemu_vfree(s->ppi.buf);
>> +    }
>> +}
>> +
>>  static void tpm_crb_class_init(ObjectClass *klass, void *data)
>>  {
>>      DeviceClass *dc = DEVICE_CLASS(klass);
>>      TPMIfClass *tc = TPM_IF_CLASS(klass);
>>  
>>      dc->realize = tpm_crb_realize;
>> +    dc->unrealize = tpm_crb_unrealize;
>>      device_class_set_props(dc, tpm_crb_properties);
>>      dc->vmsd  = &vmstate_tpm_crb;
>>      dc->user_creatable = true;
>>
>>
>>