On Thu, Aug 23, 2012 at 11:27 PM, Christoffer Dall
<c.dall@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, Aug 23, 2012 at 11:08 AM, Lei Wen <adrian.wenl@xxxxxxxxx> wrote:
>> Hi Christoffer,
>>
>> [snip]
>>
>>> diff --git a/arch/arm/kvm/init.S b/arch/arm/kvm/init.S
>>> index 1dc8926..4db26cb 100644
>>> --- a/arch/arm/kvm/init.S
>>> +++ b/arch/arm/kvm/init.S
>>> @@ -15,5 +15,135 @@
>>> * along with this program; if not, write to the Free Software
>>> * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
>>> */
>>> +
>>> +#include <linux/linkage.h>
>>> +#include <asm/unified.h>
>>> #include <asm/asm-offsets.h>
>>> #include <asm/kvm_asm.h>
>>> +#include <asm/kvm_arm.h>
>>> +
>>> +@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
>>> +@ Hypervisor initialization
>>> +@ - should be called with:
>>> +@ r0 = Hypervisor pgd pointer
>>> +@ r1 = top of Hyp stack (kernel VA)
>>> +@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
>>> + .text
>>> + .arm
>>> + .pushsection .hyp.idmap.text,"ax"
>>> + .align 12
>>> +__kvm_hyp_init:
>>> + .globl __kvm_hyp_init
>>> +
>>> + @ Hyp-mode exception vector
>>> + nop
>>> + nop
>>> + nop
>>> + nop
>>> + nop
>>> + b __do_hyp_init
>>> + nop
>>> + nop
>>> +
>>> +__do_hyp_init:
>>> + @ Set the sp to end of this page and push data for later use
>>> + mov sp, pc
>>> + bic sp, sp, #0x0ff
>>> + bic sp, sp, #0xf00
>>> + add sp, sp, #0x1000
>>> + push {r0, r1, r2, r12}
>>
>> Is safe to use the stack here? Since our HYP memory mapping is
>> gotten valid after the following HTTBR being set as I think.
>>
>
> yes, as you can see in the end of this block we have a .align 12
> before __kvm_hyp_init_end giving us the stack space we need in this
> page (as long as this init code doesn't grow beyond ~3K
I know this area is already being mapped in hyp_init_static_idmap,
however, due to the HTTBR is not being set up yet in the below code.
So how the memory get mapped in the hyp mode? I mean what I could
understand the hyp virtual address only could be seen after HTTBR
being set up.
>
>
>
>>> +
>>> + @ Set the HTTBR to point to the hypervisor PGD pointer passed to
>>> + @ function and set the upper bits equal to the kernel PGD.
>>> + mrrc p15, 1, r1, r2, c2
>>> + mcrr p15, 4, r0, r2, c2
>>> +
>>
>> [snip]
Thanks,
Lei
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