Re: [PATCH 1/1] tools/libs/light: fix BAR memory address truncation

[Jan Beulich <jbeulich@xxxxxxxx>]

On 10.10.2025 10:00, Jiqian Chen wrote:
> 64-bit BAR memory address is truncated when removing a passthrough pci
> device from guest since it uses "unsigned int".

You talking of address truncation only here, ...

> --- a/tools/libs/light/libxl_pci.c
> +++ b/tools/libs/light/libxl_pci.c
> @@ -2001,7 +2001,8 @@ static void pci_remove_detached(libxl__egc *egc,
>  {
>      STATE_AO_GC(prs->aodev->ao);
>      libxl_ctx *ctx = libxl__gc_owner(gc);
> -    unsigned int start = 0, end = 0, flags = 0, size = 0, irq = 0;
> +    unsigned long long start = 0, end = 0, flags = 0, size = 0;
> +    unsigned int irq = 0;

... does "flags" really need widening, too?

> @@ -2031,7 +2032,7 @@ static void pci_remove_detached(libxl__egc *egc,
>      }
>  
>      for (i = 0; i < PROC_PCI_NUM_RESOURCES; i++) {
> -        if (fscanf(f, "0x%x 0x%x 0x%x\n", &start, &end, &flags) != 3)
> +        if (fscanf(f, "0x%llx 0x%llx 0x%llx\n", &start, &end, &flags) != 3)

While touching this, don't we want to drop the stray 0x in here? Their
presence causes bogus input like 0x0x0 to be accepted, afaict.

> @@ -2040,7 +2041,7 @@ static void pci_remove_detached(libxl__egc *egc,
>                                                   size, 0);
>                  if (rc < 0)
>                      LOGED(ERROR, domid,
> -                          "xc_domain_ioport_permission error 0x%x/0x%x",
> +                          "xc_domain_ioport_permission error 0x%llx/0x%llx",
>                            start,
>                            size);
>              } else {
> @@ -2050,7 +2051,7 @@ static void pci_remove_detached(libxl__egc *egc,
>                                                  0);
>                  if (rc < 0)
>                      LOGED(ERROR, domid,
> -                          "xc_domain_iomem_permission error 0x%x/0x%x",
> +                          "xc_domain_iomem_permission error 0x%llx/0x%llx",

In the hypervisor I would request use of %#llx here; not sure what the
toolstack's take on this is.

Jan