Re: [PATCH v3 64/82] ppc/{ppc440_bamboo,sam460ex}: drop RAM size fixup

[BALATON Zoltan]

On Tue, 21 Jan 2020, Igor Mammedov wrote:
> If user provided non-sense RAM size, board will complain and
> continue running with max RAM size supported or sometimes
> crash like this:
>  %QEMU -M bamboo -m 1
>    exec.c:1926: find_ram_offset: Assertion `size != 0' failed.
>    Aborted (core dumped)
> Also RAM is going to be allocated by generic code, so it won't be
> possible for board to fix things up for user.
>
> Make it error message and exit to force user fix CLI,
> instead of accepting non-sense CLI values.
> That also fixes crash issue, since wrongly calculated size
> isn't used to allocate RAM
>
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
> v2:
>  * s/ppc4xx_sdram_adjust/ppc4xx_sdram_prep/
>     (BALATON Zoltan <address@hidden>)
>  * print possible valid ram size id not all RAM was distributed
>  * initialize ram_bases/ram_bases at the same time we are checking
>    that user supplied RAM would fit available banks and drop nested
>    loop that were duplicating the same calculations.
>  * coincidentally fix crash when -m is less than minimal bank size
> v3:
>  * s/ppc4xx_sdram_prep/ppc4xx_sdram_banks/
>      (BALATON Zoltan <address@hidden>)
>  * fix subject line in commit message
> v3.1
>  * add lost 'break' statement in 'j' loop
>
> CC: address@hidden
> CC: address@hidden
> CC: address@hidden
> ---
> include/hw/ppc/ppc4xx.h |  9 ++++----
> hw/ppc/ppc440_bamboo.c  | 11 ++++------
> hw/ppc/ppc4xx_devs.c    | 57 ++++++++++++++++++++++++++-----------------------
> hw/ppc/sam460ex.c       |  5 ++---
> 4 files changed, 40 insertions(+), 42 deletions(-)
>
> diff --git a/include/hw/ppc/ppc4xx.h b/include/hw/ppc/ppc4xx.h
> index 7d82259..b8c8f32 100644
> --- a/include/hw/ppc/ppc4xx.h
> +++ b/include/hw/ppc/ppc4xx.h
> @@ -42,11 +42,10 @@ enum {
> qemu_irq *ppcuic_init (CPUPPCState *env, qemu_irq *irqs,
>                        uint32_t dcr_base, int has_ssr, int has_vr);
>
> -ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int nr_banks,
> -                               MemoryRegion ram_memories[],
> -                               hwaddr ram_bases[],
> -                               hwaddr ram_sizes[],
> -                               const ram_addr_t sdram_bank_sizes[]);
> +void ppc4xx_sdram_banks(ram_addr_t ram_size, int nr_banks,
> +                        MemoryRegion ram_memories[],
> +                        hwaddr ram_bases[], hwaddr ram_sizes[],
> +                        const ram_addr_t sdram_bank_sizes[]);
>
> void ppc4xx_sdram_init (CPUPPCState *env, qemu_irq irq, int nbanks,
>                         MemoryRegion ram_memories[],
> diff --git a/hw/ppc/ppc440_bamboo.c b/hw/ppc/ppc440_bamboo.c
> index b782641..577f7c2 100644
> --- a/hw/ppc/ppc440_bamboo.c
> +++ b/hw/ppc/ppc440_bamboo.c
> @@ -158,7 +158,6 @@ static void main_cpu_reset(void *opaque)
>
> static void bamboo_init(MachineState *machine)
> {
> -    ram_addr_t ram_size = machine->ram_size;
>     const char *kernel_filename = machine->kernel_filename;
>     const char *kernel_cmdline = machine->kernel_cmdline;
>     const char *initrd_filename = machine->initrd_filename;
> @@ -203,10 +202,8 @@ static void bamboo_init(MachineState *machine)
>     /* SDRAM controller */
>     memset(ram_bases, 0, sizeof(ram_bases));
>     memset(ram_sizes, 0, sizeof(ram_sizes));
> -    ram_size = ppc4xx_sdram_adjust(ram_size, PPC440EP_SDRAM_NR_BANKS,
> -                                   ram_memories,
> -                                   ram_bases, ram_sizes,
> -                                   ppc440ep_sdram_bank_sizes);
> +    ppc4xx_sdram_banks(ram_size, PPC440EP_SDRAM_NR_BANKS, ram_memories,


Is ram_size still valid here or should this be machine->ram_size as well?


> +                       ram_bases, ram_sizes, ppc440ep_sdram_bank_sizes);
>     /* XXX 440EP's ECC interrupts are on UIC1, but we've only created UIC0. */
>     ppc4xx_sdram_init(env, pic[14], PPC440EP_SDRAM_NR_BANKS, ram_memories,
>                       ram_bases, ram_sizes, 1);
> @@ -268,7 +265,7 @@ static void bamboo_init(MachineState *machine)
>     /* Load initrd. */
>     if (initrd_filename) {
>         initrd_size = load_image_targphys(initrd_filename, RAMDISK_ADDR,
> -                                          ram_size - RAMDISK_ADDR);
> +                                          machine->ram_size - RAMDISK_ADDR);
>
>         if (initrd_size < 0) {
>             error_report("could not load ram disk '%s' at %x",
> @@ -279,7 +276,7 @@ static void bamboo_init(MachineState *machine)
>
>     /* If we're loading a kernel directly, we must load the device tree too. */
>     if (kernel_filename) {
> -        if (bamboo_load_device_tree(FDT_ADDR, ram_size, RAMDISK_ADDR,
> +        if (bamboo_load_device_tree(FDT_ADDR, machine->ram_size, RAMDISK_ADDR,
>                                     initrd_size, kernel_cmdline) < 0) {
>             error_report("couldn't load device tree");
>             exit(1);
> diff --git a/hw/ppc/ppc4xx_devs.c b/hw/ppc/ppc4xx_devs.c
> index c2e5013..5a3bb80 100644
> --- a/hw/ppc/ppc4xx_devs.c
> +++ b/hw/ppc/ppc4xx_devs.c
> @@ -673,16 +673,16 @@ void ppc4xx_sdram_init (CPUPPCState *env, qemu_irq irq, 
> int nbanks,
>  * The 4xx SDRAM controller supports a small number of banks, and each bank
>  * must be one of a small set of sizes. The number of banks and the supported
>  * sizes varies by SoC. */
> -ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int nr_banks,
> -                               MemoryRegion ram_memories[],
> -                               hwaddr ram_bases[],
> -                               hwaddr ram_sizes[],
> -                               const ram_addr_t sdram_bank_sizes[])
> +void ppc4xx_sdram_banks(ram_addr_t ram_size, int nr_banks,
> +                        MemoryRegion ram_memories[],
> +                        hwaddr ram_bases[], hwaddr ram_sizes[],
> +                        const ram_addr_t sdram_bank_sizes[])
> {
>     MemoryRegion *ram = g_malloc0(sizeof(*ram));
>     ram_addr_t size_left = ram_size;
>     ram_addr_t base = 0;
>     ram_addr_t bank_size;
> +    int last_bank = 0;
>     int i;
>     int j;
>
> @@ -690,7 +690,12 @@ ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int 
> nr_banks,
>         for (j = 0; sdram_bank_sizes[j] != 0; j++) {
>             bank_size = sdram_bank_sizes[j];
>             if (bank_size <= size_left) {

Does this blow up if values in sdram_bank_sizes are not sorted from big to 
small? If so this should be noted in the comment above.

> +                ram_bases[i] = base;
> +                ram_sizes[i] = bank_size;
> +                base += bank_size;
>                 size_left -= bank_size;
> +                last_bank = i;
> +                break;

I'm not sure how it is supposed to work. (I never knew as this is not my 
code but was there before.) AFAIU the idea was to use as many available 
bank sizes first on one ram_base before moving on to the next. This does 
not seem to do that and will go to the next ram after populating the first 
bank if I understood correctly. But the original code was also not going 
through with that and in the second loop only used the first bank selected 
so that does not make much sense.

The problem here is that e.g. sam460ex has only one RAM slot so its 
firmware does not bother checking any other slot (even if the SoC could 
handle 4 slots) so unless we put everything (possibly with different 
banks) in the first RAM slot it won't work. The other constraint is the 
SoC's memory controller that encodes ram_base and ram_size in a single 
register and only allows certain sizes.

What happens if we try to set 1.5GB or 768MB? I think SPD could represent 
that using different bank sizes even if uncommon (I wrote 
spd_data_generate() in hw/i2c/smbus_eeprom.c but that was a long ago and 
forgot about it since) but probably the ppc440 SDRAM controller does not 
have values for this size so not sure if it would work. Currently this 
functions lets 1.5G and 768M through and that much RAM is allocated but 
only 1G or 512M will be mapped.

I guess the situation is not worse after your changes with not allocating 
unmapped RAM, the machine still gets the same amount (only annoying users 
about it).

Regards,
BALATON Zoltan

>             }
>         }
>         if (!size_left) {
> @@ -699,34 +704,32 @@ ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int 
> nr_banks,
>         }
>     }
>
> -    ram_size -= size_left;
>     if (size_left) {
> -        error_report("Truncating memory to %" PRId64 " MiB to fit SDRAM"
> -                     " controller limits", ram_size / MiB);
> +        ram_addr_t used_size = ram_size - size_left;
> +        GString *s = g_string_new(NULL);
> +
> +        for (i = 0; sdram_bank_sizes[i]; i++) {
> +            g_string_append_printf(s, "%" PRIi64 "%s",
> +                                   sdram_bank_sizes[i] / MiB,
> +                                   sdram_bank_sizes[i + 1] ? " ," : "");
> +        }
> +        error_report("Max %d banks of %s MB DIMM/bank supported",
> +            nr_banks, s->str);
> +        error_report("Possible valid RAM size: %" PRIi64,
> +            used_size ? used_size / MiB : sdram_bank_sizes[i - 1] / MiB);
> +
> +        g_string_free(s, true);
> +        exit(EXIT_FAILURE);
>     }
>
>     memory_region_allocate_system_memory(ram, NULL, "ppc4xx.sdram", ram_size);
>
> -    size_left = ram_size;
> -    for (i = 0; i < nr_banks && size_left; i++) {
> -        for (j = 0; sdram_bank_sizes[j] != 0; j++) {
> -            bank_size = sdram_bank_sizes[j];
> -
> -            if (bank_size <= size_left) {
> -                char name[32];
> -                snprintf(name, sizeof(name), "ppc4xx.sdram%d", i);
> -                memory_region_init_alias(&ram_memories[i], NULL, name, ram,
> -                                         base, bank_size);
> -                ram_bases[i] = base;
> -                ram_sizes[i] = bank_size;
> -                base += bank_size;
> -                size_left -= bank_size;
> -                break;
> -            }
> -        }
> +    for (i = 0; i <= last_bank; i++) {
> +        char name[32];
> +        snprintf(name, sizeof(name), "ppc4xx.sdram%d", i);
> +        memory_region_init_alias(&ram_memories[i], NULL, name, ram,
> +                                 ram_bases[i], ram_sizes[i]);
>     }
> -
> -    return ram_size;
> }
>
> /*****************************************************************************/
> diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
> index 437e214..949acba 100644
> --- a/hw/ppc/sam460ex.c
> +++ b/hw/ppc/sam460ex.c
> @@ -324,9 +324,8 @@ static void sam460ex_init(MachineState *machine)
>     /* SDRAM controller */
>     /* put all RAM on first bank because board has one slot
>      * and firmware only checks that */
> -    machine->ram_size = ppc4xx_sdram_adjust(machine->ram_size, 1,
> -                                   ram_memories, ram_bases, ram_sizes,
> -                                   ppc460ex_sdram_bank_sizes);
> +    ppc4xx_sdram_banks(machine->ram_size, 1, ram_memories, ram_bases, 
> ram_sizes,
> +                       ppc460ex_sdram_bank_sizes);
>
>     /* FIXME: does 460EX have ECC interrupts? */
>     ppc440_sdram_init(env, SDRAM_NR_BANKS, ram_memories,