Re: [PATCH v3 64/84] ppc/{ppc440_bamboo,sam460ex}: drop RAM size fixup

[BALATON Zoltan <balaton@eik.bme.hu>]

On Mon, 20 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 <imammedo@redhat.com>
> Acked-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> v2:
>  * s/ppc4xx_sdram_adjust/ppc4xx_sdram_prep/
>     (BALATON Zoltan <balaton@eik.bme.hu>)
>  * 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 <balaton@eik.bme.hu>)
>  * fix subject line in commit message
>
> CC: balaton@eik.bme.hu
> CC: david@gibson.dropbear.id.au
> CC: qemu-ppc@nongnu.org
> ---
> include/hw/ppc/ppc4xx.h |  9 ++++----
> hw/ppc/ppc440_bamboo.c  | 11 ++++------
> hw/ppc/ppc4xx_devs.c    | 56 +++++++++++++++++++++++++------------------------
> hw/ppc/sam460ex.c       |  5 ++---
> 4 files changed, 39 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,
> +                       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..de2c87b 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 +690,11 @@ 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) {
> +                ram_bases[i] = base;
> +                ram_sizes[i] = bank_size;
> +                base += bank_size;
>                 size_left -= bank_size;
> +                last_bank = i;
>             }
>         }
>         if (!size_left) {
> @@ -699,34 +703,32 @@ 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]);
>     }

Looking at it once again I'm not sure the above change (and moving the 
remaining part of the loop in subsequent patch) is really identical. 
There's a break; in the original second for j loop which the first one's 
missing so does this still select same bank sizes and wouldn't it create 
more alias regions than it should after these patches? I have to admit I 
haven't tried to understand this function because it did what I needed for 
sam460ex so I don't know if it has any preexisting bugs.

It also appears to rely not only on sdram_bank_sizes[] being 0 terminated 
but on values being reverse sorted so that should also be mentioned in the 
comment before the function.

Regards,
BALATON Zoltan

> -
> -    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,
>