Re: [PATCH v6 14/25] ppc440_sdram: Move RAM size check to ppc440_sdram_init

From: Daniel Henrique Barboza <danielhb413@gmail.com>
To: BALATON Zoltan <balaton@eik.bme.hu>,
	qemu-devel@nongnu.org, qemu-ppc@nongnu.org
Cc: clg@kaod.org, Peter Maydell <peter.maydell@linaro.org>
Subject: Re: [PATCH v6 14/25] ppc440_sdram: Move RAM size check to ppc440_sdram_init
Date: Fri, 14 Oct 2022 19:09:39 -0300	[thread overview]
Message-ID: <d6be8094-3ab9-58e5-c4ac-a767f552e8e3@gmail.com> (raw)
In-Reply-To: <41da3797392acaacc7963b79512c8af8005fa4b0.1664021647.git.balaton@eik.bme.hu>

Zoltan,

Gitlab didn't like this patch. It broke all 32 bits builds due to an overflow
down there:

On 9/24/22 09:28, BALATON Zoltan wrote:
> Move the check for valid memory sizes from board to sdram controller
> init. This adds the missing valid memory sizes of 4 GiB, 16 and 8 MiB
> to the DoC and the board now only checks for additional restrictions
> imposed by its firmware then sdram init checks for valid sizes for SoC.
> 
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> ---
>   hw/ppc/ppc440.h    |  4 ++--
>   hw/ppc/ppc440_uc.c | 15 +++++++--------
>   hw/ppc/sam460ex.c  | 32 +++++++++++++++++---------------
>   3 files changed, 26 insertions(+), 25 deletions(-)
> 
> diff --git a/hw/ppc/ppc440.h b/hw/ppc/ppc440.h
> index 01d76b8000..29f6f14ed7 100644
> --- a/hw/ppc/ppc440.h
> +++ b/hw/ppc/ppc440.h
> @@ -11,13 +11,13 @@
>   #ifndef PPC440_H
>   #define PPC440_H
>   
> -#include "hw/ppc/ppc4xx.h"
> +#include "hw/ppc/ppc.h"
>   
>   void ppc4xx_l2sram_init(CPUPPCState *env);
>   void ppc4xx_cpr_init(CPUPPCState *env);
>   void ppc4xx_sdr_init(CPUPPCState *env);
>   void ppc440_sdram_init(CPUPPCState *env, int nbanks,
> -                       Ppc4xxSdramBank *ram_banks);
> +                       MemoryRegion *ram);
>   void ppc4xx_ahb_init(CPUPPCState *env);
>   void ppc4xx_dma_init(CPUPPCState *env, int dcr_base);
>   void ppc460ex_pcie_init(CPUPPCState *env);
> diff --git a/hw/ppc/ppc440_uc.c b/hw/ppc/ppc440_uc.c
> index edd0781eb7..2b9d666b71 100644
> --- a/hw/ppc/ppc440_uc.c
> +++ b/hw/ppc/ppc440_uc.c
> @@ -487,7 +487,7 @@ void ppc4xx_sdr_init(CPUPPCState *env)
>   typedef struct ppc440_sdram_t {
>       uint32_t addr;
>       uint32_t mcopt2;
> -    int nbanks;
> +    int nbanks; /* Banks to use from the 4, e.g. when board has less slots */
>       Ppc4xxSdramBank bank[4];
>   } ppc440_sdram_t;
>   
> @@ -733,18 +733,17 @@ static void sdram_ddr2_reset(void *opaque)
>   }
>   
>   void ppc440_sdram_init(CPUPPCState *env, int nbanks,
> -                       Ppc4xxSdramBank *ram_banks)
> +                       MemoryRegion *ram)
>   {
>       ppc440_sdram_t *s;
> -    int i;
> +    const ram_addr_t valid_bank_sizes[] = {
> +        4 * GiB, 2 * GiB, 1 * GiB, 512 * MiB, 256 * MiB, 128 * MiB, 64 * MiB,

^ here. ram_addr_t will be a 32 bit var in a 32 bit host, and assigning 4 * GiB will
overflow it back to zero.

Here's the Gitlab error from the 'cross-win32-system' runner:

FAILED: libqemu-ppc64-softmmu.fa.p/hw_ppc_ppc440_uc.c.obj
2725i686-w64-mingw32-gcc -m32 -Ilibqemu-ppc64-softmmu.fa.p -I. -I.. -Itarget/ppc -I../target/ppc -I../dtc/libfdt -Iqapi -Itrace -Iui -Iui/shader -I/usr/i686-w64-mingw32/sys-root/mingw/include/pixman-1 -I/usr/i686-w64-mingw32/sys-root/mingw/include/glib-2.0 -I/usr/i686-w64-mingw32/sys-root/mingw/lib/glib-2.0/include -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -iquote . -iquote /builds/danielhb/qemu -iquote /builds/danielhb/qemu/include -iquote /builds/danielhb/qemu/tcg/i386 -mms-bitfields -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-pie -no-pie -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-labels -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -DNEED_CPU_H '-DCONFIG_TARGET="ppc64-softmmu-config-target.h"' '-DCONFIG_DEVICES="ppc64-softmmu-config-devices.h"' -MD -MQ libqemu-ppc64-softmmu.fa.p/hw_ppc_ppc440_uc.c.obj -MF libqemu-ppc64-softmmu.fa.p/hw_ppc_ppc440_uc.c.obj.d -o libqemu-ppc64-softmmu.fa.p/hw_ppc_ppc440_uc.c.obj -c ../hw/ppc/ppc440_uc.c
2726../hw/ppc/ppc440_uc.c: In function 'ppc4xx_sdram_ddr2_realize':
2727../hw/ppc/ppc440_uc.c:729:9: error: unsigned conversion from 'long long int' to 'unsigned int' changes value from '4294967296' to '0' [-Werror=overflow]
2728  729 |         4 * GiB, 2 * GiB, 1 * GiB, 512 * MiB, 256 * MiB, 128 * MiB, 64 * MiB,
2729      |         ^
2730cc1: all warnings being treated as errors
2731

A quick fix that I can make in-tree is to avoid the overflow by doing (4 * GiB) - 1.
But since this might affect some logic in the model I figured I should ask you
first.

Let me know if this is OK with you. Otherwise feel free to propose another
workaround. I appreciate if you can answer quickly because I can't make a ppc-next
PR until this is sorted out.

Thanks,

Daniel

> +        32 * MiB, 16 * MiB, 8 * MiB, 0
> +    };
>   
>       s = g_malloc0(sizeof(*s));
>       s->nbanks = nbanks;
> -    for (i = 0; i < nbanks; i++) {
> -        s->bank[i].ram = ram_banks[i].ram;
> -        s->bank[i].base = ram_banks[i].base;
> -        s->bank[i].size = ram_banks[i].size;
> -    }
> +    ppc4xx_sdram_banks(ram, s->nbanks, s->bank, valid_bank_sizes);
>       qemu_register_reset(&sdram_ddr2_reset, s);
>       ppc_dcr_register(env, SDRAM0_CFGADDR,
>                        s, &sdram_ddr2_dcr_read, &sdram_ddr2_dcr_write);
> diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
> index b318521b01..13055a8916 100644
> --- a/hw/ppc/sam460ex.c
> +++ b/hw/ppc/sam460ex.c
> @@ -74,13 +74,6 @@
>   #define EBC_FREQ 115000000
>   #define UART_FREQ 11059200
>   
> -/* The SoC could also handle 4 GiB but firmware does not work with that. */
> -/* Maybe it overflows a signed 32 bit number somewhere? */
> -static const ram_addr_t ppc460ex_sdram_bank_sizes[] = {
> -    2 * GiB, 1 * GiB, 512 * MiB, 256 * MiB, 128 * MiB, 64 * MiB,
> -    32 * MiB, 0
> -};
> -
>   struct boot_info {
>       uint32_t dt_base;
>       uint32_t dt_size;
> @@ -273,7 +266,6 @@ static void sam460ex_init(MachineState *machine)
>   {
>       MemoryRegion *address_space_mem = get_system_memory();
>       MemoryRegion *isa = g_new(MemoryRegion, 1);
> -    Ppc4xxSdramBank *ram_banks = g_new0(Ppc4xxSdramBank, 1);
>       MemoryRegion *l2cache_ram = g_new(MemoryRegion, 1);
>       DeviceState *uic[4];
>       int i;
> @@ -340,12 +332,22 @@ static void sam460ex_init(MachineState *machine)
>       }
>   
>       /* SDRAM controller */
> -    /* put all RAM on first bank because board has one slot
> -     * and firmware only checks that */
> -    ppc4xx_sdram_banks(machine->ram, 1, ram_banks, ppc460ex_sdram_bank_sizes);
> -
> +    /* The SoC could also handle 4 GiB but firmware does not work with that. */
> +    if (machine->ram_size > 2 * GiB) {
> +        error_report("Memory over 2 GiB is not supported");
> +        exit(1);
> +    }
> +    /* Firmware needs at least 64 MiB */
> +    if (machine->ram_size < 64 * MiB) {
> +        error_report("Memory below 64 MiB is not supported");
> +        exit(1);
> +    }
> +    /*
> +     * Put all RAM on first bank because board has one slot
> +     * and firmware only checks that
> +     */
> +    ppc440_sdram_init(env, 1, machine->ram);
>       /* FIXME: does 460EX have ECC interrupts? */
> -    ppc440_sdram_init(env, 1, ram_banks);
>       /* Enable SDRAM memory regions as we may boot without firmware */
>       ppc4xx_sdram_ddr2_enable(env);
>   
> @@ -354,8 +356,8 @@ static void sam460ex_init(MachineState *machine)
>                                  qdev_get_gpio_in(uic[0], 2));
>       i2c = PPC4xx_I2C(dev)->bus;
>       /* SPD EEPROM on RAM module */
> -    spd_data = spd_data_generate(ram_banks->size < 128 * MiB ? DDR : DDR2,
> -                                 ram_banks->size);
> +    spd_data = spd_data_generate(machine->ram_size < 128 * MiB ? DDR : DDR2,
> +                                 machine->ram_size);
>       spd_data[20] = 4; /* SO-DIMM module */
>       smbus_eeprom_init_one(i2c, 0x50, spd_data);
>       /* RTC */