2017-06-09 08:26:27

by Hu Huajun

Subject: [PATCH] KVM: ARM64: fix phy counter access failure in guest.

When reading the cntpct_el0 in guest with VHE (Virtual Host Extension)
enabled in host, the "Unsupported guest sys_reg access" error reported.
The reason is cnthctl_el2.EL1PCTEN is not enabled, which is expected
to be done in kvm_timer_init_vhe(). The problem is kvm_timer_init_vhe
is called by cpu_init_hyp_mode, and which is called when VHE is disabled.
This patch calls kvm_timer_init_vhe() to enable cnthctl_el2.EL1PCTEN
in cpu_hyp_reinit().

Signed-off-by: Hu Huajun <[email protected]>
---
virt/kvm/arm/arm.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 3417e18..b703741 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1137,6 +1137,7 @@ static void cpu_hyp_reinit(void)
* event was cancelled before the CPU was reset.
*/
__cpu_init_stage2();
+ kvm_timer_init_vhe();
} else {
cpu_init_hyp_mode(NULL);
}
--
2.10.1

2017-06-09 08:41:43

by Christoffer Dall

Subject: Re: [PATCH] KVM: ARM64: fix phy counter access failure in guest.

Hi,

On Sat, Jun 10, 2017 at 12:22:20AM +0800, Hu Huajun wrote:
> When reading the cntpct_el0 in guest with VHE (Virtual Host Extension)
> enabled in host, the "Unsupported guest sys_reg access" error reported.
> The reason is cnthctl_el2.EL1PCTEN is not enabled, which is expected
> to be done in kvm_timer_init_vhe(). The problem is kvm_timer_init_vhe
> is called by cpu_init_hyp_mode, and which is called when VHE is disabled.
> This patch calls kvm_timer_init_vhe() to enable cnthctl_el2.EL1PCTEN
> in cpu_hyp_reinit().
>
> Signed-off-by: Hu Huajun <[email protected]>
> ---
> virt/kvm/arm/arm.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 3417e18..b703741 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -1137,6 +1137,7 @@ static void cpu_hyp_reinit(void)
> * event was cancelled before the CPU was reset.
> */
> __cpu_init_stage2();
> + kvm_timer_init_vhe();
> } else {
> cpu_init_hyp_mode(NULL);
> }
> --
> 2.10.1
>

Could you rework this patch to remove the incorrect call to
kvm_timer_init_vhe() from cpu_init_hyp_mode() as well?

Thanks,
-Christoffer