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

[Stefan Berger]

On 1/13/22 05:37, Eric Auger wrote:

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.

The change in meson.build is required to include the
cpu.h header.

Signed-off-by: Eric Auger <eric.au...@redhat.com>

Suspend/resume tested it:

Tested-by: Stefan Berger <stef...@linux.ibm.com>

---
  hw/tpm/meson.build |  2 +-
  hw/tpm/tpm_crb.c   | 10 ++++++++--
  2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/hw/tpm/meson.build b/hw/tpm/meson.build
index 1c68d81d6a..3e74df945b 100644
--- a/hw/tpm/meson.build
+++ b/hw/tpm/meson.build
@@ -1,8 +1,8 @@
  softmmu_ss.add(when: 'CONFIG_TPM_TIS', if_true: files('tpm_tis_common.c'))
  softmmu_ss.add(when: 'CONFIG_TPM_TIS_ISA', if_true: files('tpm_tis_isa.c'))
  softmmu_ss.add(when: 'CONFIG_TPM_TIS_SYSBUS', if_true: 
files('tpm_tis_sysbus.c'))
-softmmu_ss.add(when: 'CONFIG_TPM_CRB', if_true: files('tpm_crb.c'))

+specific_ss.add(when: 'CONFIG_TPM_CRB', if_true: files('tpm_crb.c'))
  specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TPM_TIS'], if_true: 
files('tpm_ppi.c'))
  specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TPM_CRB'], if_true: 
files('tpm_ppi.c'))
  specific_ss.add(when: 'CONFIG_TPM_SPAPR', if_true: files('tpm_spapr.c'))
diff --git a/hw/tpm/tpm_crb.c b/hw/tpm/tpm_crb.c
index 58ebd1469c..25f8e685e4 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 "cpu.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));

      memory_region_add_subregion(get_system_memory(),
          TPM_CRB_ADDR_BASE, &s->mmio);