Re: [PATCH] x86: cpu: Error out if memory exceeds addressable range

[Nikunj A. Dadhania]

On 7/18/2022 6:12 PM, Igor Mammedov wrote:
> On Mon, 18 Jul 2022 13:47:34 +0530
> Nikunj A Dadhania <nikunj@amd.com> wrote:
> 
>> Currently it is possible to start a guest with memory that is beyond
>> the addressable range of CPU and QEMU does not even warn about it.
>> The default phys_bits is 40 and can address 1TB. However it allows to
>> start a guest with greater than 1TB memory.
>>
>> Prevent this by erroring out in such a scenario.
>>
>> Reported-by: Shaju Abraham <Abraham.Shaju@amd.com>
>> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
> 
> 
> Following shall care of your issue:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg900136.html

Thanks, I tried out the patch series, I could start guest till 978G (not sure 
why this magic number yet) and after that I start getting errors:

$ ./build/qemu-system-x86_64 -enable-kvm  -machine q35 -m 979G  -kernel bzImage 
-initrd initramfs.cpio -vga none -nographic -append "console=ttyS0,115200n8 
earlyprintk=serial,ttyS0,115200 debug=1 " -nodefaults -serial stdio
qemu-system-x86_64: Address space limit 0xffffffffff < 0x1fc3fffffff phys-bits 
too low (40)

Regards
Nikunj