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
>> +
>> + @ 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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