qemu/hw/xen/xen_pt_load_rom.c
Akihiko Odaki 6a67577d80 hw/pci: Replace -1 with UINT32_MAX for romsize
romsize is an uint32_t variable. Specifying -1 as an uint32_t value is
obscure way to denote UINT32_MAX.

Worse, if int is wider than 32-bit, it will change the behavior of a
construct like the following:
romsize = -1;
if (romsize != -1) {
    ...
}

When -1 is assigned to romsize, -1 will be implicitly casted into
uint32_t, resulting in UINT32_MAX. On contrary, when evaluating
romsize != -1, romsize will be casted into int, and it will be a
comparison of UINT32_MAX and -1, and result in false.

Replace -1 with UINT32_MAX for statements involving the variable to
clarify the intent and prevent potential breakage.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20240627-reuse-v10-10-7ca0b8ed3d9f@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2024-07-03 18:14:07 -04:00

93 lines
2.8 KiB
C

/*
* This is splited from hw/i386/kvm/pci-assign.c
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "hw/loader.h"
#include "hw/pci/pci.h"
#include "xen_pt.h"
/*
* Scan the assigned devices for the devices that have an option ROM, and then
* load the corresponding ROM data to RAM. If an error occurs while loading an
* option ROM, we just ignore that option ROM and continue with the next one.
*/
void *pci_assign_dev_load_option_rom(PCIDevice *dev,
int *size, unsigned int domain,
unsigned int bus, unsigned int slot,
unsigned int function)
{
char name[32], rom_file[64];
FILE *fp;
uint8_t val;
struct stat st;
void *ptr = NULL;
Object *owner = OBJECT(dev);
/* If loading ROM from file, pci handles it */
if (dev->romfile || !dev->rom_bar) {
return NULL;
}
snprintf(rom_file, sizeof(rom_file),
"/sys/bus/pci/devices/%04x:%02x:%02x.%01x/rom",
domain, bus, slot, function);
/* Write "1" to the ROM file to enable it */
fp = fopen(rom_file, "r+");
if (fp == NULL) {
if (errno != ENOENT) {
error_report("pci-assign: Cannot open %s: %s", rom_file, strerror(errno));
}
return NULL;
}
if (fstat(fileno(fp), &st) == -1) {
error_report("pci-assign: Cannot stat %s: %s", rom_file, strerror(errno));
goto close_rom;
}
val = 1;
if (fwrite(&val, 1, 1, fp) != 1) {
goto close_rom;
}
fseek(fp, 0, SEEK_SET);
if (dev->romsize != UINT_MAX) {
if (st.st_size > dev->romsize) {
error_report("ROM BAR \"%s\" (%ld bytes) is too large for ROM size %u",
rom_file, (long) st.st_size, dev->romsize);
goto close_rom;
}
} else {
dev->romsize = st.st_size;
}
snprintf(name, sizeof(name), "%s.rom", object_get_typename(owner));
memory_region_init_ram(&dev->rom, owner, name, dev->romsize, &error_abort);
ptr = memory_region_get_ram_ptr(&dev->rom);
memset(ptr, 0xff, dev->romsize);
if (!fread(ptr, 1, st.st_size, fp)) {
error_report("pci-assign: Cannot read from host %s", rom_file);
error_printf("Device option ROM contents are probably invalid "
"(check dmesg).\nSkip option ROM probe with rombar=0, "
"or load from file with romfile=\n");
goto close_rom;
}
pci_register_bar(dev, PCI_ROM_SLOT, 0, &dev->rom);
dev->has_rom = true;
*size = st.st_size;
close_rom:
/* Write "0" to disable ROM */
fseek(fp, 0, SEEK_SET);
val = 0;
if (!fwrite(&val, 1, 1, fp)) {
XEN_PT_WARN(dev, "%s\n", "Failed to disable pci-sysfs rom file");
}
fclose(fp);
return ptr;
}