hw/i386/pc: run the multiboot loader before the PVH loader

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

Posted by Stefano Garzarella 6 years, 8 months ago

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 <pbonzini@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 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;
     }
 
-- 
2.20.1

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

Posted by Michael S. Tsirkin 6 years, 8 months ago

On Thu, Feb 14, 2019 at 07:02:16PM +0100, Stefano Garzarella wrote:
> 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 <pbonzini@redhat.com>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Paolo can you pls merge since you did the pvh things?

> ---
>  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;
>      }
>  
> -- 
> 2.20.1

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

Posted by Paolo Bonzini 6 years, 8 months ago

On 14/02/19 20:09, Michael S. Tsirkin wrote:
> On Thu, Feb 14, 2019 at 07:02:16PM +0100, Stefano Garzarella wrote:
>> 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 <pbonzini@redhat.com>
>> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> 
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> 
> Paolo can you pls merge since you did the pvh things?

Yes, queued.

Paolo

>> ---
>>  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;
>>      }
>>  
>> -- 
>> 2.20.1

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

Posted by Alex Bennée 6 years, 8 months ago

Stefano Garzarella <sgarzare@redhat.com> 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 <pbonzini@redhat.com>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  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