On Feb 18, 2013, at 1:44 AM, Gleb Natapov wrote:
> On Fri, Feb 15, 2013 at 11:10:46AM -0500, Sanjay Lal wrote:
>>
>> On Feb 6, 2013, at 8:20 AM, Gleb Natapov wrote:
>>
>>> On Wed, Nov 21, 2012 at 06:34:09PM -0800, Sanjay Lal wrote:
>>>> +static gpa_t kvm_trap_emul_gva_to_gpa_cb(gva_t gva)
>>>> +{
>>>> + gpa_t gpa;
>>>> + uint32_t kseg = KSEGX(gva);
>>>> +
>>>> + if ((kseg == CKSEG0) || (kseg == CKSEG1))
>>> You seems to be using KVM_GUEST_KSEGX variants on gva in all other
>>> places. Why not here?
>>
>> This function is invoked to handle 2 scenarios:
>> (1) Parse the boot code config tables setup by QEMU's Malta emulation. The pointers in the tables are actual KSEG0 addresses (unmapped, cached) and not Guest KSEG0 addresses.
>>
> Where is it called for that purpose? The only place where gva_to_gpa
> callback is called is in kvm/kvm_mips_emul.c:kvm_mips_emulate_(store|load)
Load/stores from/to KSEG1 generate the Address Error Load/Store exceptions. The handler calls kvm_mips_emul.c:kvm_mips_emulate_(store|load) which then call the gva_to_gpa callback.
>
>> (2) Handle I/O accesses by the guest. On MIPS platforms, I/O device registers are mapped into the KSEG1 address space (unmapped, uncached). Again like (1) these are actual KSEG1 addresses, which cause an exception and are passed onto QEMU for I/O emulation.
>>
> So guest KSEG1 registers is mapped to 0xA0000000-0xBFFFFFFF ranges just
> like on a host? Can you give corresponding segment names to those ranges
>
> Guest User address space: 0x00000000 -> 0x40000000 (useg?)
> Guest Kernel Unmapped: 0x40000000 -> 0x60000000 (kseg0?)
> Guest Kernel Mapped: 0x60000000 -> 0x80000000 (?)
>
Yes, now that you mention it :-). I'll add a corresponding Guest Kernel KSEG1 segment name.
Regards
Sanjay
