linux-kernel - [PATCH v2] KVM: ARM64: fix phy counter access failure in guest.

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Date:   Mon, 12 Jun 2017 22:37:48 +0800
From:   Hu Huajun <huhuajun@...wei.com>
To:     <christoffer.dall@...aro.org>, <marc.zyngier@....com>,
        <rkrcmar@...hat.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <songwenjun@...wei.com>,
        <gengdongjiu@...wei.com>, <huhuajun@...wei.com>
Subject: [PATCH v2] 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 remove the incorrect call to kvm_timer_init_vhe() from
cpu_init_hyp_mode(), and calls kvm_timer_init_vhe() to enable
cnthctl_el2.EL1PCTEN in cpu_hyp_reinit().

Changes from v1:
* According to Christoffer Dall's comment, remove the incocrrect call
to kvm_timer_init_vhe() in cpu_init_hyp_mode().

Signed-off-by: Hu Huajun <huhuajun@...wei.com>
---
 virt/kvm/arm/arm.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 3417e18..a430125 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1115,9 +1115,6 @@ static void cpu_init_hyp_mode(void *dummy)
 	__cpu_init_hyp_mode(pgd_ptr, hyp_stack_ptr, vector_ptr);
 	__cpu_init_stage2();

-	if (is_kernel_in_hyp_mode())
-		kvm_timer_init_vhe();
-
 	kvm_arm_init_debug();
 }

@@ -1137,6 +1134,7 @@ 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