diff mbox series

[47/59] KVM: arm64: nv: Propagate CNTVOFF_EL2 to the virtual EL1 timer

Message ID 20190621093843.220980-48-marc.zyngier@arm.com (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: ARMv8.3 Nested Virtualization support | expand

Commit Message

Marc Zyngier June 21, 2019, 9:38 a.m. UTC 
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 <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/kvm_host.h |  1 -
 arch/arm64/kvm/sys_regs.c         |  8 ++++++--
 include/kvm/arm_arch_timer.h      |  1 +
 virt/kvm/arm/arch_timer.c         | 12 ++++++++++++
 4 files changed, 19 insertions(+), 3 deletions(-)

Comments

Alexandru Elisei Aug. 8, 2019, 9:34 a.m. UTC | #1 
On 6/21/19 10:38 AM, Marc Zyngier wrote:
> 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 <marc.zyngier@arm.com>
> ---
>  arch/arm64/include/asm/kvm_host.h |  1 -
>  arch/arm64/kvm/sys_regs.c         |  8 ++++++--
>  include/kvm/arm_arch_timer.h      |  1 +
>  virt/kvm/arm/arch_timer.c         | 12 ++++++++++++
>  4 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index b7c44adcdbf3..e0fe9acb46bf 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -252,7 +252,6 @@ 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 1b8016330a19..2031a59fcf49 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -150,7 +150,6 @@ struct el2_sysreg_map {
>  	PURE_EL2_SYSREG( RVBAR_EL2 ),
>  	PURE_EL2_SYSREG( RMR_EL2 ),
>  	PURE_EL2_SYSREG( TPIDR_EL2 ),
> -	PURE_EL2_SYSREG( CNTVOFF_EL2 ),
>  	PURE_EL2_SYSREG( CNTHCTL_EL2 ),
>  	PURE_EL2_SYSREG( HPFAR_EL2 ),
>  	EL2_SYSREG(      SCTLR_EL2,  SCTLR_EL1,      translate_sctlr ),
> @@ -1351,6 +1350,11 @@ 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();
>  	}
> @@ -2122,7 +2126,7 @@ 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 3d84c240071d..1d53352c7d97 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -913,6 +913,10 @@ 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();
>  	}
> @@ -955,6 +959,10 @@ 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();
>  	}
> @@ -1166,6 +1174,10 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
>  		return -EINVAL;
>  	}
>  
> +	/* Nested virtualization requires zero offset for virtual EL2 */
> +	if (nested_virt_in_use(vcpu))
> +		vcpu_vtimer(vcpu)->cntvoff = 0;

I think this is related to the fact that the virtual offset is treated as 0 when
reading CNTVCT_EL0 from EL2, or from from EL2 and EL0 if E2H, TGE are set
(please correct me if I'm wrong).

However, when the guest runs in virtual EL2, the direct_vtimer is the hvtimer,
so the value that ends up in CNTVOFF_EL2 is vcpu_hvtimer(vcpu)->cntvoff.

Thanks,
Alex
> +
>  	get_timer_map(vcpu, &map);
>  
>  	ret = kvm_vgic_map_phys_irq(vcpu,
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index b7c44adcdbf3..e0fe9acb46bf 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -252,7 +252,6 @@  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 1b8016330a19..2031a59fcf49 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -150,7 +150,6 @@  struct el2_sysreg_map {
 	PURE_EL2_SYSREG( RVBAR_EL2 ),
 	PURE_EL2_SYSREG( RMR_EL2 ),
 	PURE_EL2_SYSREG( TPIDR_EL2 ),
-	PURE_EL2_SYSREG( CNTVOFF_EL2 ),
 	PURE_EL2_SYSREG( CNTHCTL_EL2 ),
 	PURE_EL2_SYSREG( HPFAR_EL2 ),
 	EL2_SYSREG(      SCTLR_EL2,  SCTLR_EL1,      translate_sctlr ),
@@ -1351,6 +1350,11 @@  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();
 	}
@@ -2122,7 +2126,7 @@  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 3d84c240071d..1d53352c7d97 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -913,6 +913,10 @@  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();
 	}
@@ -955,6 +959,10 @@  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();
 	}
@@ -1166,6 +1174,10 @@  int kvm_timer_enable(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 	}
 
+	/* Nested virtualization requires zero offset for virtual EL2 */
+	if (nested_virt_in_use(vcpu))
+		vcpu_vtimer(vcpu)->cntvoff = 0;
+
 	get_timer_map(vcpu, &map);
 
 	ret = kvm_vgic_map_phys_irq(vcpu,