Re: [Qemu-devel] [PATCH] hw/i386/pc: run the multiboot loader before the PVH loader

[Alex Bennée]

Stefano Garzarella <address@hidden> writes:

> Some multiboot images could be in the ELF format. In the current
> implementation QEMU fails because we try to load these images
> as a PVH image.
>
> In order to fix this issue, we should try multiboot first (we
> already check the multiboot magic header before to load it).
> If it is not a multiboot image, we can try the PVH loader.
>
> Fixes: ab969087da6 ("pvh: Boot uncompressed kernel using direct boot ABI", 
> 2019-01-15)
> Reported-by: Paolo Bonzini <address@hidden>
> Signed-off-by: Stefano Garzarella <address@hidden>

Reviewed-by: Alex Bennée <address@hidden>
Tested-by: Alex Bennée <address@hidden>

> ---
>  hw/i386/pc.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 3889eccdc3..207c267093 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1209,6 +1209,17 @@ static void load_linux(PCMachineState *pcms,
>      if (ldl_p(header+0x202) == 0x53726448) {
>          protocol = lduw_p(header+0x206);
>      } else {
> +        /*
> +         * This could be a multiboot kernel. If it is, let's stop treating it
> +         * like a Linux kernel.
> +         * Note: some multiboot images could be in the ELF format (the same 
> of
> +         * PVH), so we try multiboot first since we check the multiboot magic
> +         * header before to load it.
> +         */
> +        if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
> +                           kernel_cmdline, kernel_size, header)) {
> +            return;
> +        }
>          /*
>           * Check if the file is an uncompressed kernel file (ELF) and load 
> it,
>           * saving the PVH entry point used by the x86/HVM direct boot ABI.
> @@ -1262,12 +1273,6 @@ static void load_linux(PCMachineState *pcms,
>
>              return;
>          }
> -        /* This looks like a multiboot kernel. If it is, let's stop
> -           treating it like a Linux kernel. */
> -        if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
> -                           kernel_cmdline, kernel_size, header)) {
> -            return;
> -        }
>          protocol = 0;
>      }


--
Alex Bennée