Re: [PATCH v13 06/10] ACPI ERST: build the ACPI ERST table

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jan 25, 2022 at 10:32:45AM -0600, Eric DeVolder wrote:
> Hi Michael,
> Thanks for examining this! Inline response below.
> eric
> 
> On 1/25/22 06:05, Michael S. Tsirkin wrote:
> > On Tue, Jan 25, 2022 at 04:23:49PM +0530, Ani Sinha wrote:
> > > 
> > > 
> > > On Mon, 24 Jan 2022, Eric DeVolder wrote:
> > > 
> > > > This builds the ACPI ERST table to inform OSPM how to communicate
> > > > with the acpi-erst device.
> > > > 
> > > > Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
> > > > ---
> > > >   hw/acpi/erst.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > > >   1 file changed, 188 insertions(+)
> > > > 
> > > > diff --git a/hw/acpi/erst.c b/hw/acpi/erst.c
> > > > index fe9ba51..b0c7539 100644
> > > > --- a/hw/acpi/erst.c
> > > > +++ b/hw/acpi/erst.c
> > > > @@ -59,6 +59,27 @@
> > > >   #define STATUS_RECORD_STORE_EMPTY     0x04
> > > >   #define STATUS_RECORD_NOT_FOUND       0x05
> > > > 
> > > > +/* ACPI 4.0: Table 17-19 Serialization Instructions */
> > > > +#define INST_READ_REGISTER                 0x00
> > > > +#define INST_READ_REGISTER_VALUE           0x01
> > > > +#define INST_WRITE_REGISTER                0x02
> > > > +#define INST_WRITE_REGISTER_VALUE          0x03
> > > > +#define INST_NOOP                          0x04
> > > > +#define INST_LOAD_VAR1                     0x05
> > > > +#define INST_LOAD_VAR2                     0x06
> > > > +#define INST_STORE_VAR1                    0x07
> > > > +#define INST_ADD                           0x08
> > > > +#define INST_SUBTRACT                      0x09
> > > > +#define INST_ADD_VALUE                     0x0A
> > > > +#define INST_SUBTRACT_VALUE                0x0B
> > > > +#define INST_STALL                         0x0C
> > > > +#define INST_STALL_WHILE_TRUE              0x0D
> > > > +#define INST_SKIP_NEXT_INSTRUCTION_IF_TRUE 0x0E
> > > > +#define INST_GOTO                          0x0F
> > > > +#define INST_SET_SRC_ADDRESS_BASE          0x10
> > > > +#define INST_SET_DST_ADDRESS_BASE          0x11
> > > > +#define INST_MOVE_DATA                     0x12
> > > > +
> > > >   /* UEFI 2.1: Appendix N Common Platform Error Record */
> > > >   #define UEFI_CPER_RECORD_MIN_SIZE 128U
> > > >   #define UEFI_CPER_RECORD_LENGTH_OFFSET 20U
> > > > @@ -172,6 +193,173 @@ typedef struct {
> > > > 
> > > >   /*******************************************************************/
> > > >   /*******************************************************************/
> > > > +
> > > > +/* ACPI 4.0: 17.4.1.2 Serialization Instruction Entries */
> > > > +static void build_serialization_instruction_entry(GArray *table_data,
> > > > +    uint8_t serialization_action,
> > > > +    uint8_t instruction,
> > > > +    uint8_t flags,
> > > > +    uint8_t register_bit_width,
> > > > +    uint64_t register_address,
> > > > +    uint64_t value)
> > > > +{
> > > > +    /* ACPI 4.0: Table 17-18 Serialization Instruction Entry */
> > > > +    struct AcpiGenericAddress gas;
> > > > +    uint64_t mask;
> > > > +
> > > > +    /* Serialization Action */
> > > > +    build_append_int_noprefix(table_data, serialization_action, 1);
> > > > +    /* Instruction */
> > > > +    build_append_int_noprefix(table_data, instruction         , 1);
> > > > +    /* Flags */
> > > > +    build_append_int_noprefix(table_data, flags               , 1);
> > > > +    /* Reserved */
> > > > +    build_append_int_noprefix(table_data, 0                   , 1);
> > > > +    /* Register Region */
> > > > +    gas.space_id = AML_SYSTEM_MEMORY;
> > > > +    gas.bit_width = register_bit_width;
> > > > +    gas.bit_offset = 0;
> > > > +    gas.access_width = ctz32(register_bit_width) - 2;
> > > > +    gas.address = register_address;
> > > > +    build_append_gas_from_struct(table_data, &gas);
> > > > +    /* Value */
> > > > +    build_append_int_noprefix(table_data, value  , 8);
> > > > +    /* Mask */
> > > > +    mask = (1ULL << (register_bit_width - 1) << 1) - 1;
> > > > +    build_append_int_noprefix(table_data, mask  , 8);
> > > > +}
> > > > +
> > > > +/* ACPI 4.0: 17.4.1 Serialization Action Table */
> > > > +void build_erst(GArray *table_data, BIOSLinker *linker, Object *erst_dev,
> > > > +    const char *oem_id, const char *oem_table_id)
> > > > +{
> > > > +    GArray *table_instruction_data;
> > > > +    unsigned action;
> > > > +    pcibus_t bar0 = pci_get_bar_addr(PCI_DEVICE(erst_dev), 0);
> > > > +    AcpiTable table = { .sig = "ERST", .rev = 1, .oem_id = oem_id,
> > > > +                        .oem_table_id = oem_table_id };
> > > > +
> > > > +    trace_acpi_erst_pci_bar_0(bar0);
> > > > +
> > > > +    /*
> > > > +     * Serialization Action Table
> > > > +     * The serialization action table must be generated first
> > > > +     * so that its size can be known in order to populate the
> > > > +     * Instruction Entry Count field.
> > > > +     */
> > > > +    table_instruction_data = g_array_new(FALSE, FALSE, sizeof(char));
> > > > +
> > > > +    /*
> > > > +     * Macros for use with construction of the action instructions
> > > > +     */
> > > > +#define BUILD_READ_REGISTER(width_in_bits, reg) \
> > > > +    build_serialization_instruction_entry(table_instruction_data, \
> > > > +        action, INST_READ_REGISTER, 0, width_in_bits, \
> > > > +        bar0 + reg, 0)
> > > > +
> > > > +#define BUILD_READ_REGISTER_VALUE(width_in_bits, reg, value) \
> > > > +    build_serialization_instruction_entry(table_instruction_data, \
> > > > +        action, INST_READ_REGISTER_VALUE, 0, width_in_bits, \
> > > > +        bar0 + reg, value)
> > > > +
> > > > +#define BUILD_WRITE_REGISTER(width_in_bits, reg, value) \
> > > > +    build_serialization_instruction_entry(table_instruction_data, \
> > > > +        action, INST_WRITE_REGISTER, 0, width_in_bits, \
> > > > +        bar0 + reg, value)
> > > > +
> > > > +#define BUILD_WRITE_REGISTER_VALUE(width_in_bits, reg, value) \
> > > > +    build_serialization_instruction_entry(table_instruction_data, \
> > > > +        action, INST_WRITE_REGISTER_VALUE, 0, width_in_bits, \
> > > > +        bar0 + reg, value)
> > 
> > 
> > I think these macros which in a hidden way use the bar0 variable really
> > should be replaced with inline functions, improving type safety.
> 
> I had not stated this previously, but my choice for using macros over functions
> was the use three local variables: table_instruction_data, bar0, and action.

Oh, didn't notice the others too.

> Any function would then automatically require these three as parameters, or I'm
> stuffing these temporary items into local globals (to avoid passing as parameters).

Please, no globals.


> As for the type safety of bar0, I don't quite understand what I should do differently
> (regardless of macro vs function). Ultimately these call build_serialization_instruction_entry()
> with the 'uint64_t register address' accepting the bar0+offset value. Bar0 is pcibar_t
> and the compiler happily implicitly typecasts to uint64_t.

The other way could warn though - maybe we should build with
-Wconversion. That's going to require quite a bit of work though.

> What would an acceptable function prototype look like?

Well, that's a limitation of C. We can pass a
structure if you really need to save some code lines but that's really
all we can do.

> 
> > 
> > 
> > 
> > 
> > > > +
> > > > +    /* Serialization Instruction Entries */
> > > > +    action = ACTION_BEGIN_WRITE_OPERATION;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_BEGIN_READ_OPERATION;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_BEGIN_CLEAR_OPERATION;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_END_OPERATION;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_SET_RECORD_OFFSET;
> > > > +    BUILD_WRITE_REGISTER(32, ERST_VALUE_OFFSET, 0);
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_EXECUTE_OPERATION;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_VALUE_OFFSET,
> > > > +        ERST_EXECUTE_OPERATION_MAGIC);
> > > 
> > > except here, on all cases we have
> > > BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > 
> > > We should treat the above as special case and simplify the rest of the
> > > calls (eliminate repeated common arguments).
> > > 
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_CHECK_BUSY_STATUS;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER_VALUE(32, ERST_VALUE_OFFSET, 0x01);
> > > > +
> > > > +    action = ACTION_GET_COMMAND_STATUS;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(32, ERST_VALUE_OFFSET);
> > > > +
> > > > +    action = ACTION_GET_RECORD_IDENTIFIER;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(64, ERST_VALUE_OFFSET);
> > > > +
> > > > +    action = ACTION_SET_RECORD_IDENTIFIER;
> > > > +    BUILD_WRITE_REGISTER(64, ERST_VALUE_OFFSET, 0);
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > 
> > > This one seems reverted. Should this be
> > > BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > BUILD_WRITE_REGISTER(64, ERST_VALUE_OFFSET, 0);
> > > 
> > > like others?
> > > 
> > > > +
> > > > +    action = ACTION_GET_RECORD_COUNT;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(32, ERST_VALUE_OFFSET);
> > > > +
> > > > +    action = ACTION_BEGIN_DUMMY_WRITE_OPERATION;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +
> > > > +    action = ACTION_GET_ERROR_LOG_ADDRESS_RANGE;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(64, ERST_VALUE_OFFSET);
> > > > +
> > > > +    action = ACTION_GET_ERROR_LOG_ADDRESS_LENGTH;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(64, ERST_VALUE_OFFSET);
> > > > +
> > > > +    action = ACTION_GET_ERROR_LOG_ADDRESS_RANGE_ATTRIBUTES;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(32, ERST_VALUE_OFFSET);
> > > > +
> > > > +    action = ACTION_GET_EXECUTE_OPERATION_TIMINGS;
> > > > +    BUILD_WRITE_REGISTER_VALUE(32, ERST_ACTION_OFFSET, action);
> > > > +    BUILD_READ_REGISTER(64, ERST_VALUE_OFFSET);
> > > > +
> > > 
> > > BUILD_READ_REGISTER() is always called with ERST_VALUE_OFFSET as second
> > > argument. WE should eliminate this repeated passing of same argument.
> > > 
> > > 
> > > > +    /* Serialization Header */
> > > > +    acpi_table_begin(&table, table_data);
> > > > +
> > > > +    /* Serialization Header Size */
> > > > +    build_append_int_noprefix(table_data, 48, 4);
> > > > +
> > > > +    /* Reserved */
> > > > +    build_append_int_noprefix(table_data,  0, 4);
> > > > +
> > > > +    /*
> > > > +     * Instruction Entry Count
> > > > +     * Each instruction entry is 32 bytes
> > > > +     */
> > > > +    g_assert((table_instruction_data->len) % 32 == 0);
> > > > +    build_append_int_noprefix(table_data,
> > > > +        (table_instruction_data->len / 32), 4);
> > > > +
> > > > +    /* Serialization Instruction Entries */
> > > > +    g_array_append_vals(table_data, table_instruction_data->data,
> > > > +        table_instruction_data->len);
> > > > +    g_array_free(table_instruction_data, TRUE);
> > > > +
> > > > +    acpi_table_end(linker, &table);
> > > > +}
> > > > +
> > > > +/*******************************************************************/
> > > > +/*******************************************************************/
> > > >   static uint8_t *get_nvram_ptr_by_index(ERSTDeviceState *s, unsigned index)
> > > >   {
> > > >       uint8_t *rc = NULL;
> > > > --
> > > > 1.8.3.1
> > > > 
> > > > 
> >