[PATCH v2 49/94] KVM: arm64: nv: Propagate CNTVOFF_EL2 to the virtual EL1 timer

[Marc Zyngier]

We need to allow a guest hypervisor to virtualize the virtual timer.
FOr that, let's propagate CNTVOFF_EL2 to the guest's view of that
timer.

Signed-off-by: Marc Zyngier <m...@kernel.org>
---
 arch/arm64/include/asm/kvm_host.h | 1 -
 arch/arm64/kvm/sys_regs.c         | 7 ++++++-
 include/kvm/arm_arch_timer.h      | 1 +
 virt/kvm/arm/arch_timer.c         | 8 ++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h 
b/arch/arm64/include/asm/kvm_host.h
index 36bb463dc16a..e35165de51a2 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -247,7 +247,6 @@ enum vcpu_sysreg {
        RMR_EL2,        /* Reset Management Register */
        CONTEXTIDR_EL2, /* Context ID Register (EL2) */
        TPIDR_EL2,      /* EL2 Software Thread ID Register */
-       CNTVOFF_EL2,    /* Counter-timer Virtual Offset register */
        CNTHCTL_EL2,    /* Counter-timer Hypervisor Control register */
        SP_EL2,         /* EL2 Stack Pointer */
 
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 5d9ca3988745..7e2553480721 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1373,6 +1373,11 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
                tmr = TIMER_PTIMER;
                treg = TIMER_REG_CVAL;
                break;
+       case SYS_CNTVOFF_EL2:
+               tmr = TIMER_VTIMER;
+               treg = TIMER_REG_VOFF;
+               break;
+
        default:
                BUG();
        }
@@ -2075,7 +2080,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
        { SYS_DESC(SYS_CONTEXTIDR_EL2), access_rw, reset_val, CONTEXTIDR_EL2, 0 
},
        { SYS_DESC(SYS_TPIDR_EL2), access_rw, reset_val, TPIDR_EL2, 0 },
 
-       { SYS_DESC(SYS_CNTVOFF_EL2), access_rw, reset_val, CNTVOFF_EL2, 0 },
+       { SYS_DESC(SYS_CNTVOFF_EL2), access_arch_timer },
        { SYS_DESC(SYS_CNTHCTL_EL2), access_rw, reset_val, CNTHCTL_EL2, 0 },
 
        { SYS_DESC(SYS_CNTHP_TVAL_EL2), access_arch_timer },
diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index 3a5d9255120e..3389606f3029 100644
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -23,6 +23,7 @@ enum kvm_arch_timer_regs {
        TIMER_REG_CVAL,
        TIMER_REG_TVAL,
        TIMER_REG_CTL,
+       TIMER_REG_VOFF,
 };
 
 struct arch_timer_context {
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index c7edefced838..3c88a4c0a296 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -917,6 +917,10 @@ static u64 kvm_arm_timer_read(struct kvm_vcpu *vcpu,
                val = kvm_phys_timer_read() - timer->cntvoff;
                break;
 
+       case TIMER_REG_VOFF:
+               val = timer->cntvoff;
+               break;
+
        default:
                BUG();
        }
@@ -959,6 +963,10 @@ static void kvm_arm_timer_write(struct kvm_vcpu *vcpu,
                timer->cnt_cval = val;
                break;
 
+       case TIMER_REG_VOFF:
+               timer->cntvoff = val;
+               break;
+
        default:
                BUG();
        }
-- 
2.20.1

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