Re: [PATCH v4 04/10] target-mips: get_physical_address: Add KVM awareness

[James Hogan <james.hogan@imgtec.com>]

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On 19/03/14 16:33, Paolo Bonzini wrote:
> Il 14/03/2014 13:47, James Hogan ha scritto:
>> +    if (kvm_enabled()) {
>> +        /* KVM T&E adds guest kernel segments in useg */
>> +        if (real_address >= KVM_KSEG0_BASE) {
>> +            if (real_address < KVM_KSEG2_BASE) {
>> +                /* kseg0 */
>> +                address += KSEG0_BASE - KVM_KSEG0_BASE;
>> +            } else if (real_address <= USEG_LIMIT) {
>> +                /* kseg2/3 */
>> +                address += KSEG2_BASE - KVM_KSEG2_BASE;
>> +            }
>> +        }
>> +    }
> 
> Besides changing the segment bases, is there anything else to do to run
> KVM-enabled kernels under TCG?  (I know nothing about MIPS and it
> shows).  We should consider adding a knob to run them in TCG mode.
> 
> This is not blocking this series, and I'm okay with helping or even
> doing the work, if somebody tells me what to do. :)

That's a good idea. It's pretty much just the extra segments I think. In
TCG mode the bootloader wouldn't even need to do anything different
since it can translate fine from the reset vector in kseg1 (where a KVM
guest cannot execute from) and it'll still jump to the kernel entry
point from the ELF.

I'll add it to my list :)

Cheers
James


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