Geoff,
On 03/24/2015 01:46 AM, Geoff Levand wrote:
> Hi Takahiro,
>
> On Mon, 2015-03-23 at 20:53 +0900, AKASHI Takahiro wrote:
>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>> index 3e6859b..428f41c 100644
>> --- a/arch/arm/kvm/mmu.c
>> +++ b/arch/arm/kvm/mmu.c
> ...
>> +phys_addr_t kvm_get_stub_vectors(void)
>> +{
>> + return virt_to_phys(__hyp_stub_vectors);
>> +}
>
> The stub vectors are not part of KVM, but part of kernel,
> so to me a routine get_hyp_stub_vectors() with a prototype
> in asm/virt.h, then a definition in maybe
> kernel/process.c, or a new file kernel/virt.c makes more
> sense.
Right.
Will rename the function to get_hyp_stub_vectors() and put it in asm/virt.h.
>> +unsigned long kvm_reset_func_entry(void)
>> +{
>> + /* VA of __kvm_hyp_reset in trampline code */
>> + return TRAMPOLINE_VA + (__kvm_hyp_reset - __hyp_idmap_text_start);
>> +}
>> +
>> int kvm_mmu_init(void)
>> {
>> int err;
>> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
>> index 4f7310f..97ee2fc 100644
>> --- a/arch/arm64/include/asm/kvm_asm.h
>> +++ b/arch/arm64/include/asm/kvm_asm.h
>> @@ -116,8 +116,11 @@
>> struct kvm;
>> struct kvm_vcpu;
>>
>> +extern char __hyp_stub_vectors[];
>
> I think this should at least be in asm/virt.h, or better,
> have a get_hyp_stub_vectors().
See above.
>> extern char __kvm_hyp_init[];
>> extern char __kvm_hyp_init_end[];
>> +extern char __kvm_hyp_reset[];
>>
>> extern char __kvm_hyp_vector[];
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 8ac3c70..97f88fe 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -199,6 +199,7 @@ struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
>> struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
>>
>> u64 kvm_call_hyp(void *hypfn, ...);
>> +void kvm_call_reset(unsigned long reset_func, ...);
>
> kvm_call_reset() takes a fixed number of args, so we shouldn't
> have it as a variadic here. I think a variadic routine
> complicates things for my kvm_call_reset() suggestion below.
>
>> void force_vm_exit(const cpumask_t *mask);
>> void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>>
>> @@ -223,6 +224,15 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
>> hyp_stack_ptr, vector_ptr);
>> }
>>
>> +static inline void __cpu_reset_hyp_mode(unsigned long reset_func,
>> + phys_addr_t boot_pgd_ptr,
>> + phys_addr_t phys_idmap_start,
>> + unsigned long stub_vector_ptr)
>
>> + kvm_call_reset(reset_func, boot_pgd_ptr,
>> + phys_idmap_start, stub_vector_ptr);
>
> Why not switch the order of the args here to:
>
> kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr, reset_func)
>
> This will eliminate the register shifting in the HVC_RESET
> hcall vector which becomes just 'br x3'.
Looks nice.
FYI, initially I wanted to implement kvm_cpu_reset() using kvm_call_hyp()
and so both have similar code.
>
>> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
>> index fd085ec..aee75f9 100644
>> --- a/arch/arm64/kvm/hyp.S
>> +++ b/arch/arm64/kvm/hyp.S
>> @@ -1136,6 +1136,11 @@ ENTRY(kvm_call_hyp)
>> ret
>> ENDPROC(kvm_call_hyp)
>>
>> +ENTRY(kvm_call_reset)
>> + hvc #HVC_RESET
>> + ret
>> +ENDPROC(kvm_call_reset)
>> +
>> .macro invalid_vector label, target
>> .align 2
>> \label:
>> @@ -1179,10 +1184,10 @@ el1_sync: // Guest trapped into EL2
>> cmp x18, #HVC_GET_VECTORS
>> b.ne 1f
>> mrs x0, vbar_el2
>> - b 2f
>> -
>> -1: /* Default to HVC_CALL_HYP. */
>
> It seems you are deleting this comment and also
> removing the logic that makes HVC_CALL_HYP the default.
Yeah, I didn't think of that.
But IIUC, we don't have to handle it as default case because
all interfaces come from kvm_call_hyp() once KVM is initialized.
>> + b 3f
>>
>> +1: cmp x18, #HVC_CALL_HYP
>> + b.ne 2f
>> push lr, xzr
>>
>> /*
>> @@ -1196,7 +1201,23 @@ el1_sync: // Guest trapped into EL2
>> blr lr
>>
>> pop lr, xzr
>> -2: eret
>> + b 3f
>> +
>> + /*
>> + * shuffle the parameters and jump into trampline code.
>> + */
>> +2: cmp x18, #HVC_RESET
>> + b.ne 3f
>> +
>> + mov x18, x0
>> + mov x0, x1
>> + mov x1, x2
>> + mov x2, x3
>> + mov x3, x4
>> + br x18
>> + /* not reach here */
>> +
>> +3: eret
>
> We don't need to change labels for each new hcall, I
> think just this is OK:
>
> cmp x18, #HVC_GET_VECTORS
> b.ne 1f
> mrs x0, vbar_el2
> b 2f
>
> +1: cmp x18, #HVC_RESET
> + b.ne 1f
> + br x3 // No return
>
> 1: /* Default to HVC_CALL_HYP. */
> ...
Will fix it.
Thanks,
-Takahiro AKASHI
> -Geoff
>
>
>
