[PATCH v3 0/4] acpi: Set proper maximum size for "etc/table-loader" blob

[PATCH v3 0/4] acpi: Set proper maximum size for "etc/table-loader" blob

[David Hildenbrand]

Fix and cleanup initializing the maximum size of mutable ACPI blobs.

v1/v2 -> v3:
- 'acpi: Set proper maximum size for "etc/table-loader" blob'
-- Move "etc/table-loader" change to separate patch
-- Extend description
-- Fixup maximum size (now really use 64k)
- Add some patches to cleanup/refactor the code. I avoided using a new
  enum for the different tables for now, using the table names should be
  good enough and is simple.

David Hildenbrand (4):
  acpi: Set proper maximum size for "etc/table-loader" blob
  microvm: Don't open-code "etc/table-loader"
  acpi: Move maximum size logic into acpi_add_rom_blob()
  acpi: Set proper maximum size for "etc/acpi/rsdp" blob

 hw/acpi/utils.c             | 17 +++++++++++++++--
 hw/arm/virt-acpi-build.c    | 12 ++++++------
 hw/i386/acpi-build.c        |  7 +++----
 hw/i386/acpi-microvm.c      | 16 ++++++----------
 include/hw/acpi/aml-build.h |  3 ---
 include/hw/acpi/utils.h     |  3 +--
 6 files changed, 31 insertions(+), 27 deletions(-)

-- 
2.29.2

[PATCH v3 1/4] acpi: Set proper maximum size for "etc/table-loader" blob

[David Hildenbrand]

The resizeable memory region / RAMBlock that is created for the cmd blob
has a maximum size of whole host pages (e.g., 4k), because RAMBlocks
work on full host pages. In addition, in i386 ACPI code:
  acpi_align_size(tables->linker->cmd_blob, ACPI_BUILD_ALIGN_SIZE);
makes sure to align to multiples of 4k, padding with 0.

For example, if our cmd_blob is created with a size of 2k, the maximum
size is 4k - we cannot grow beyond that. Growing might be required
due to guest action when rebuilding the tables, but also on incoming
migration.

This automatic generation of the maximum size used to be sufficient,
however, there are cases where we cross host pages now when growing at
runtime: we exceed the maximum size of the RAMBlock and can crash QEMU when
trying to resize the resizeable memory region / RAMBlock:
  $ build/qemu-system-x86_64 --enable-kvm \
      -machine q35,nvdimm=on \
      -smp 1 \
      -cpu host \
      -m size=2G,slots=8,maxmem=4G \
      -object memory-backend-file,id=mem0,mem-path=/tmp/nvdimm,size=256M \
      -device nvdimm,label-size=131072,memdev=mem0,id=nvdimm0,slot=1 \
      -nodefaults \
      -device vmgenid \
      -device intel-iommu

Results in:
  Unexpected error in qemu_ram_resize() at ../softmmu/physmem.c:1850:
  qemu-system-x86_64: Size too large: /rom@etc/table-loader:
    0x2000 > 0x1000: Invalid argument

In this configuration, we consume exactly 4k (32 entries, 128 bytes each)
when creating the VM. However, once the guest boots up and maps the MCFG,
we also create the MCFG table and end up consuming 2 additional entries
(pointer + checksum) -- which is where we try resizing the memory region
/ RAMBlock, however, the maximum size does not allow for it.

Currently, we get the following maximum sizes for our different
mutable tables based on behavior of resizeable RAMBlock:

  hw       table                max_size
  -------  ---------------------------------------------------------

  virt     "etc/acpi/tables"    ACPI_BUILD_TABLE_MAX_SIZE (0x200000)
  virt     "etc/table-loader"   HOST_PAGE_ALIGN(initial_size)
  virt     "etc/acpi/rsdp"      HOST_PAGE_ALIGN(initial_size)

  i386     "etc/acpi/tables"    ACPI_BUILD_TABLE_MAX_SIZE (0x200000)
  i386     "etc/table-loader"   HOST_PAGE_ALIGN(initial_size)
  i386     "etc/acpi/rsdp"      HOST_PAGE_ALIGN(initial_size)

  microvm  "etc/acpi/tables"    ACPI_BUILD_TABLE_MAX_SIZE (0x200000)
  microvm  "etc/table-loader"   HOST_PAGE_ALIGN(initial_size)
  microvm  "etc/acpi/rsdp"      HOST_PAGE_ALIGN(initial_size)

Let's set the maximum table size for "etc/table-loader" to 64k, so we
can properly grow at runtime, which should be good enough for the future.

Migration is not concerned with the maximum size of a RAMBlock, only
with the used size - so existing setups are not affected. Of course, we
cannot migrate a VM that would have crash when started on older QEMU from
new QEMU to older QEMU without failing early on the destination when
synchronizing the RAM state:
    qemu-system-x86_64: Size too large: /rom@etc/table-loader: 0x2000 > 0x1000: Invalid argument
    qemu-system-x86_64: error while loading state for instance 0x0 of device 'ram'
    qemu-system-x86_64: load of migration failed: Invalid argument

We'll refactor the code next, to make sure we get rid of this implicit
behavior for "etc/acpi/rsdp" as well and to make the code easier to
grasp.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/arm/virt-acpi-build.c    | 3 ++-
 hw/i386/acpi-build.c        | 3 ++-
 hw/i386/acpi-microvm.c      | 2 +-
 include/hw/acpi/aml-build.h | 1 +
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index f9c9df916c..a91550de6f 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -865,7 +865,8 @@ void virt_acpi_setup(VirtMachineState *vms)
 
     build_state->linker_mr =
         acpi_add_rom_blob(virt_acpi_build_update, build_state,
-                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE, 0);
+                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE,
+                          ACPI_BUILD_LOADER_MAX_SIZE);
 
     fw_cfg_add_file(vms->fw_cfg, ACPI_BUILD_TPMLOG_FILE, tables.tcpalog->data,
                     acpi_data_len(tables.tcpalog));
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 31a5f6f4a5..a75138ea5a 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -2524,7 +2524,8 @@ void acpi_setup(void)
 
     build_state->linker_mr =
         acpi_add_rom_blob(acpi_build_update, build_state,
-                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE, 0);
+                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE,
+                          ACPI_BUILD_LOADER_MAX_SIZE);
 
     fw_cfg_add_file(x86ms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
                     tables.tcpalog->data, acpi_data_len(tables.tcpalog));
diff --git a/hw/i386/acpi-microvm.c b/hw/i386/acpi-microvm.c
index 54b3af478a..01f1945ac1 100644
--- a/hw/i386/acpi-microvm.c
+++ b/hw/i386/acpi-microvm.c
@@ -255,7 +255,7 @@ void acpi_setup_microvm(MicrovmMachineState *mms)
                       ACPI_BUILD_TABLE_MAX_SIZE);
     acpi_add_rom_blob(acpi_build_no_update, NULL,
                       tables.linker->cmd_blob,
-                      "etc/table-loader", 0);
+                      "etc/table-loader", ACPI_BUILD_LOADER_MAX_SIZE);
     acpi_add_rom_blob(acpi_build_no_update, NULL,
                       tables.rsdp,
                       ACPI_BUILD_RSDP_FILE, 0);
diff --git a/include/hw/acpi/aml-build.h b/include/hw/acpi/aml-build.h
index 380d3e3924..a22c6a4c86 100644
--- a/include/hw/acpi/aml-build.h
+++ b/include/hw/acpi/aml-build.h
@@ -6,6 +6,7 @@
 
 /* Reserve RAM space for tables: add another order of magnitude. */
 #define ACPI_BUILD_TABLE_MAX_SIZE         0x200000
+#define ACPI_BUILD_LOADER_MAX_SIZE        0x10000
 
 #define ACPI_BUILD_APPNAME6 "BOCHS "
 #define ACPI_BUILD_APPNAME8 "BXPC    "
-- 
2.29.2

[PATCH v3 2/4] microvm: Don't open-code "etc/table-loader"

[David Hildenbrand]

Let's just reuse ACPI_BUILD_LOADER_FILE.

Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/i386/acpi-microvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/i386/acpi-microvm.c b/hw/i386/acpi-microvm.c
index 01f1945ac1..502aac0ba2 100644
--- a/hw/i386/acpi-microvm.c
+++ b/hw/i386/acpi-microvm.c
@@ -255,7 +255,7 @@ void acpi_setup_microvm(MicrovmMachineState *mms)
                       ACPI_BUILD_TABLE_MAX_SIZE);
     acpi_add_rom_blob(acpi_build_no_update, NULL,
                       tables.linker->cmd_blob,
-                      "etc/table-loader", ACPI_BUILD_LOADER_MAX_SIZE);
+                      ACPI_BUILD_LOADER_FILE, ACPI_BUILD_LOADER_MAX_SIZE);
     acpi_add_rom_blob(acpi_build_no_update, NULL,
                       tables.rsdp,
                       ACPI_BUILD_RSDP_FILE, 0);
-- 
2.29.2

[PATCH v3 3/4] acpi: Move maximum size logic into acpi_add_rom_blob()

[David Hildenbrand]

We want to have safety margins for all tables based on the table type.
Let's move the maximum size logic into acpi_add_rom_blob() and make it
dependent on the table name, so we don't have to replicate for each and
every instance that creates such tables.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/acpi/utils.c             | 12 ++++++++++--
 hw/arm/virt-acpi-build.c    | 13 ++++++-------
 hw/i386/acpi-build.c        |  8 +++-----
 hw/i386/acpi-microvm.c      | 16 ++++++----------
 include/hw/acpi/aml-build.h |  4 ----
 include/hw/acpi/utils.h     |  3 +--
 6 files changed, 26 insertions(+), 30 deletions(-)

diff --git a/hw/acpi/utils.c b/hw/acpi/utils.c
index a134a4d554..f2d69a6d92 100644
--- a/hw/acpi/utils.c
+++ b/hw/acpi/utils.c
@@ -27,9 +27,17 @@
 #include "hw/loader.h"
 
 MemoryRegion *acpi_add_rom_blob(FWCfgCallback update, void *opaque,
-                                GArray *blob, const char *name,
-                                uint64_t max_size)
+                                GArray *blob, const char *name)
 {
+    uint64_t max_size = 0;
+
+    /* Reserve RAM space for tables: add another order of magnitude. */
+    if (!strcmp(name, ACPI_BUILD_TABLE_FILE)) {
+        max_size = 0x200000;
+    } else if (!strcmp(name, ACPI_BUILD_LOADER_FILE)) {
+        max_size = 0x10000;
+    }
+
     return rom_add_blob(name, blob->data, acpi_data_len(blob), max_size, -1,
                         name, update, opaque, NULL, true);
 }
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index a91550de6f..f5a2b2d4cb 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -859,14 +859,13 @@ void virt_acpi_setup(VirtMachineState *vms)
     /* Now expose it all to Guest */
     build_state->table_mr = acpi_add_rom_blob(virt_acpi_build_update,
                                               build_state, tables.table_data,
-                                              ACPI_BUILD_TABLE_FILE,
-                                              ACPI_BUILD_TABLE_MAX_SIZE);
+                                              ACPI_BUILD_TABLE_FILE);
     assert(build_state->table_mr != NULL);
 
-    build_state->linker_mr =
-        acpi_add_rom_blob(virt_acpi_build_update, build_state,
-                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE,
-                          ACPI_BUILD_LOADER_MAX_SIZE);
+    build_state->linker_mr = acpi_add_rom_blob(virt_acpi_build_update,
+                                               build_state,
+                                               tables.linker->cmd_blob,
+                                               ACPI_BUILD_LOADER_FILE);
 
     fw_cfg_add_file(vms->fw_cfg, ACPI_BUILD_TPMLOG_FILE, tables.tcpalog->data,
                     acpi_data_len(tables.tcpalog));
@@ -880,7 +879,7 @@ void virt_acpi_setup(VirtMachineState *vms)
 
     build_state->rsdp_mr = acpi_add_rom_blob(virt_acpi_build_update,
                                              build_state, tables.rsdp,
-                                             ACPI_BUILD_RSDP_FILE, 0);
+                                             ACPI_BUILD_RSDP_FILE);
 
     qemu_register_reset(virt_acpi_build_reset, build_state);
     virt_acpi_build_reset(build_state);
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index a75138ea5a..8de7722cfd 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -2518,14 +2518,12 @@ void acpi_setup(void)
     /* Now expose it all to Guest */
     build_state->table_mr = acpi_add_rom_blob(acpi_build_update,
                                               build_state, tables.table_data,
-                                              ACPI_BUILD_TABLE_FILE,
-                                              ACPI_BUILD_TABLE_MAX_SIZE);
+                                              ACPI_BUILD_TABLE_FILE);
     assert(build_state->table_mr != NULL);
 
     build_state->linker_mr =
         acpi_add_rom_blob(acpi_build_update, build_state,
-                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE,
-                          ACPI_BUILD_LOADER_MAX_SIZE);
+                          tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE);
 
     fw_cfg_add_file(x86ms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
                     tables.tcpalog->data, acpi_data_len(tables.tcpalog));
@@ -2564,7 +2562,7 @@ void acpi_setup(void)
         build_state->rsdp = NULL;
         build_state->rsdp_mr = acpi_add_rom_blob(acpi_build_update,
                                                  build_state, tables.rsdp,
-                                                 ACPI_BUILD_RSDP_FILE, 0);
+                                                 ACPI_BUILD_RSDP_FILE);
     }
 
     qemu_register_reset(acpi_build_reset, build_state);
diff --git a/hw/i386/acpi-microvm.c b/hw/i386/acpi-microvm.c
index 502aac0ba2..271710eb92 100644
--- a/hw/i386/acpi-microvm.c
+++ b/hw/i386/acpi-microvm.c
@@ -249,16 +249,12 @@ void acpi_setup_microvm(MicrovmMachineState *mms)
     acpi_build_microvm(&tables, mms);
 
     /* Now expose it all to Guest */
-    acpi_add_rom_blob(acpi_build_no_update, NULL,
-                      tables.table_data,
-                      ACPI_BUILD_TABLE_FILE,
-                      ACPI_BUILD_TABLE_MAX_SIZE);
-    acpi_add_rom_blob(acpi_build_no_update, NULL,
-                      tables.linker->cmd_blob,
-                      ACPI_BUILD_LOADER_FILE, ACPI_BUILD_LOADER_MAX_SIZE);
-    acpi_add_rom_blob(acpi_build_no_update, NULL,
-                      tables.rsdp,
-                      ACPI_BUILD_RSDP_FILE, 0);
+    acpi_add_rom_blob(acpi_build_no_update, NULL, tables.table_data,
+                      ACPI_BUILD_TABLE_FILE);
+    acpi_add_rom_blob(acpi_build_no_update, NULL, tables.linker->cmd_blob,
+                      ACPI_BUILD_LOADER_FILE);
+    acpi_add_rom_blob(acpi_build_no_update, NULL, tables.rsdp,
+                      ACPI_BUILD_RSDP_FILE);
 
     acpi_build_tables_cleanup(&tables, false);
 }
diff --git a/include/hw/acpi/aml-build.h b/include/hw/acpi/aml-build.h
index a22c6a4c86..15b069186d 100644
--- a/include/hw/acpi/aml-build.h
+++ b/include/hw/acpi/aml-build.h
@@ -4,10 +4,6 @@
 #include "hw/acpi/acpi-defs.h"
 #include "hw/acpi/bios-linker-loader.h"
 
-/* Reserve RAM space for tables: add another order of magnitude. */
-#define ACPI_BUILD_TABLE_MAX_SIZE         0x200000
-#define ACPI_BUILD_LOADER_MAX_SIZE        0x10000
-
 #define ACPI_BUILD_APPNAME6 "BOCHS "
 #define ACPI_BUILD_APPNAME8 "BXPC    "
 
diff --git a/include/hw/acpi/utils.h b/include/hw/acpi/utils.h
index 140b4de603..0022df027d 100644
--- a/include/hw/acpi/utils.h
+++ b/include/hw/acpi/utils.h
@@ -4,6 +4,5 @@
 #include "hw/nvram/fw_cfg.h"
 
 MemoryRegion *acpi_add_rom_blob(FWCfgCallback update, void *opaque,
-                                GArray *blob, const char *name,
-                                uint64_t max_size);
+                                GArray *blob, const char *name);
 #endif
-- 
2.29.2

[PATCH v3 4/4] acpi: Set proper maximum size for "etc/acpi/rsdp" blob

[David Hildenbrand]

Let's also set a maximum size for "etc/acpi/rsdp", so the maximum
size doesn't get implicitly set based on the initial table size. In my
experiments, the table size was in the range of 22 bytes, so a single
page (== what we used until now) seems to be good enough.

Now that we have defined maximum sizes for all currently used table types,
let's assert that we catch usage with new tables that need a proper maximum
size definition.

Also assert that our initial size does not exceed the maximum size; while
qemu_ram_alloc_internal() properly asserts that the initial RAMBlock size
is <= its maximum size, the result might differ when the host page size
is bigger than 4k.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/acpi/utils.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/acpi/utils.c b/hw/acpi/utils.c
index f2d69a6d92..0c486ea29f 100644
--- a/hw/acpi/utils.c
+++ b/hw/acpi/utils.c
@@ -29,14 +29,19 @@
 MemoryRegion *acpi_add_rom_blob(FWCfgCallback update, void *opaque,
                                 GArray *blob, const char *name)
 {
-    uint64_t max_size = 0;
+    uint64_t max_size;
 
     /* Reserve RAM space for tables: add another order of magnitude. */
     if (!strcmp(name, ACPI_BUILD_TABLE_FILE)) {
         max_size = 0x200000;
     } else if (!strcmp(name, ACPI_BUILD_LOADER_FILE)) {
         max_size = 0x10000;
+    } else if (!strcmp(name, ACPI_BUILD_RSDP_FILE)) {
+        max_size = 0x1000;
+    } else {
+        g_assert_not_reached();
     }
+    g_assert(acpi_data_len(blob) <= max_size);
 
     return rom_add_blob(name, blob->data, acpi_data_len(blob), max_size, -1,
                         name, update, opaque, NULL, true);
-- 
2.29.2

Re: [PATCH v3 4/4] acpi: Set proper maximum size for "etc/acpi/rsdp" blob

[Igor Mammedov]

On Thu,  4 Mar 2021 11:55:54 +0100
David Hildenbrand <david@redhat.com> wrote:

> Let's also set a maximum size for "etc/acpi/rsdp", so the maximum
> size doesn't get implicitly set based on the initial table size. In my
> experiments, the table size was in the range of 22 bytes, so a single
> page (== what we used until now) seems to be good enough.
> 
> Now that we have defined maximum sizes for all currently used table types,
> let's assert that we catch usage with new tables that need a proper maximum
> size definition.
> 
> Also assert that our initial size does not exceed the maximum size; while
> qemu_ram_alloc_internal() properly asserts that the initial RAMBlock size
> is <= its maximum size, the result might differ when the host page size
> is bigger than 4k.
> 
> Suggested-by: Laszlo Ersek <lersek@redhat.com>
> Cc: Alistair Francis <alistair.francis@xilinx.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Peter Maydell <peter.maydell@linaro.org>
> Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/acpi/utils.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/acpi/utils.c b/hw/acpi/utils.c
> index f2d69a6d92..0c486ea29f 100644
> --- a/hw/acpi/utils.c
> +++ b/hw/acpi/utils.c
> @@ -29,14 +29,19 @@
>  MemoryRegion *acpi_add_rom_blob(FWCfgCallback update, void *opaque,
>                                  GArray *blob, const char *name)
>  {
> -    uint64_t max_size = 0;
> +    uint64_t max_size;
[...]
> +    } else {
> +        g_assert_not_reached();
>      }
> +    g_assert(acpi_data_len(blob) <= max_size);

though it's correct,
but theoretically compiler might get unhappy about uninitialized max_size here

though if it compiles fine with our current CI it should be good enough

>  
>      return rom_add_blob(name, blob->data, acpi_data_len(blob), max_size, -1,
>                          name, update, opaque, NULL, true);

Re: [PATCH v3 4/4] acpi: Set proper maximum size for "etc/acpi/rsdp" blob

[David Hildenbrand]

On 15.03.21 12:54, Igor Mammedov wrote:
> On Thu,  4 Mar 2021 11:55:54 +0100
> David Hildenbrand <david@redhat.com> wrote:
> 
>> Let's also set a maximum size for "etc/acpi/rsdp", so the maximum
>> size doesn't get implicitly set based on the initial table size. In my
>> experiments, the table size was in the range of 22 bytes, so a single
>> page (== what we used until now) seems to be good enough.
>>
>> Now that we have defined maximum sizes for all currently used table types,
>> let's assert that we catch usage with new tables that need a proper maximum
>> size definition.
>>
>> Also assert that our initial size does not exceed the maximum size; while
>> qemu_ram_alloc_internal() properly asserts that the initial RAMBlock size
>> is <= its maximum size, the result might differ when the host page size
>> is bigger than 4k.
>>
>> Suggested-by: Laszlo Ersek <lersek@redhat.com>
>> Cc: Alistair Francis <alistair.francis@xilinx.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: "Michael S. Tsirkin" <mst@redhat.com>
>> Cc: Igor Mammedov <imammedo@redhat.com>
>> Cc: Peter Maydell <peter.maydell@linaro.org>
>> Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
>> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Richard Henderson <richard.henderson@linaro.org>
>> Cc: Laszlo Ersek <lersek@redhat.com>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>   hw/acpi/utils.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/acpi/utils.c b/hw/acpi/utils.c
>> index f2d69a6d92..0c486ea29f 100644
>> --- a/hw/acpi/utils.c
>> +++ b/hw/acpi/utils.c
>> @@ -29,14 +29,19 @@
>>   MemoryRegion *acpi_add_rom_blob(FWCfgCallback update, void *opaque,
>>                                   GArray *blob, const char *name)
>>   {
>> -    uint64_t max_size = 0;
>> +    uint64_t max_size;
> [...]
>> +    } else {
>> +        g_assert_not_reached();
>>       }
>> +    g_assert(acpi_data_len(blob) <= max_size);
> 
> though it's correct,
> but theoretically compiler might get unhappy about uninitialized max_size here
> 
> though if it compiles fine with our current CI it should be good enough

I think the compiler will respect g_assert_not_reached() as intended and 
suppress warnings.

For example, see block/qed.c:qed_aio_write_data() where be don't have a 
return statement on g_assert_not_reached() exit paths.

-- 
Thanks,

David / dhildenb

Re: [PATCH v3 0/4] acpi: Set proper maximum size for "etc/table-loader" blob

[Laszlo Ersek]

On 03/04/21 11:55, David Hildenbrand wrote:
> Fix and cleanup initializing the maximum size of mutable ACPI blobs.
> 
> v1/v2 -> v3:
> - 'acpi: Set proper maximum size for "etc/table-loader" blob'
> -- Move "etc/table-loader" change to separate patch
> -- Extend description
> -- Fixup maximum size (now really use 64k)
> - Add some patches to cleanup/refactor the code. I avoided using a new
>   enum for the different tables for now, using the table names should be
>   good enough and is simple.
> 
> David Hildenbrand (4):
>   acpi: Set proper maximum size for "etc/table-loader" blob
>   microvm: Don't open-code "etc/table-loader"
>   acpi: Move maximum size logic into acpi_add_rom_blob()
>   acpi: Set proper maximum size for "etc/acpi/rsdp" blob
> 
>  hw/acpi/utils.c             | 17 +++++++++++++++--
>  hw/arm/virt-acpi-build.c    | 12 ++++++------
>  hw/i386/acpi-build.c        |  7 +++----
>  hw/i386/acpi-microvm.c      | 16 ++++++----------
>  include/hw/acpi/aml-build.h |  3 ---
>  include/hw/acpi/utils.h     |  3 +--
>  6 files changed, 31 insertions(+), 27 deletions(-)
> 

series
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Re: [PATCH v3 0/4] acpi: Set proper maximum size for "etc/table-loader" blob

[David Hildenbrand]

On 04.03.21 11:55, David Hildenbrand wrote:
> Fix and cleanup initializing the maximum size of mutable ACPI blobs.
> 
> v1/v2 -> v3:
> - 'acpi: Set proper maximum size for "etc/table-loader" blob'
> -- Move "etc/table-loader" change to separate patch
> -- Extend description
> -- Fixup maximum size (now really use 64k)
> - Add some patches to cleanup/refactor the code. I avoided using a new
>    enum for the different tables for now, using the table names should be
>    good enough and is simple.
> 

Ping, would be nice to get this into v6.0


-- 
Thanks,

David / dhildenb

Re: [PATCH v3 0/4] acpi: Set proper maximum size for "etc/table-loader" blob

[Igor Mammedov]

On Thu,  4 Mar 2021 11:55:50 +0100
David Hildenbrand <david@redhat.com> wrote:

> Fix and cleanup initializing the maximum size of mutable ACPI blobs.
> 
> v1/v2 -> v3:
> - 'acpi: Set proper maximum size for "etc/table-loader" blob'
> -- Move "etc/table-loader" change to separate patch
> -- Extend description
> -- Fixup maximum size (now really use 64k)
> - Add some patches to cleanup/refactor the code. I avoided using a new
>   enum for the different tables for now, using the table names should be
>   good enough and is simple.
> 
> David Hildenbrand (4):
>   acpi: Set proper maximum size for "etc/table-loader" blob
>   microvm: Don't open-code "etc/table-loader"
>   acpi: Move maximum size logic into acpi_add_rom_blob()
>   acpi: Set proper maximum size for "etc/acpi/rsdp" blob
> 
>  hw/acpi/utils.c             | 17 +++++++++++++++--
>  hw/arm/virt-acpi-build.c    | 12 ++++++------
>  hw/i386/acpi-build.c        |  7 +++----
>  hw/i386/acpi-microvm.c      | 16 ++++++----------
>  include/hw/acpi/aml-build.h |  3 ---
>  include/hw/acpi/utils.h     |  3 +--
>  6 files changed, 31 insertions(+), 27 deletions(-)
> 

Reviewed-by: Igor Mammedov <imammedo@redhat.com>