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[45/89] KVM: arm64: Add the {flush,sync}_timer_state() primitives

Message ID 20220519134204.5379-46-will@kernel.org (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Base support for the pKVM hypervisor at EL2 | expand

Commit Message

Will Deacon May 19, 2022, 1:41 p.m. UTC 
From: Marc Zyngier <maz@kernel.org>

In preparation for save/restore of the timer state at EL2 for protected
VMs, introduce a couple of sync/flush primitives for the architected
timer, in much the same way as we have for the GIC.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 34 ++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
diff mbox series

Patch

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 58515e5d24ec..32e7e1cad00f 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -63,6 +63,38 @@  static void sync_vgic_state(struct kvm_vcpu *host_vcpu,
 		WRITE_ONCE(host_cpu_if->vgic_lr[i], shadow_cpu_if->vgic_lr[i]);
 }
 
+static void flush_timer_state(struct kvm_shadow_vcpu_state *shadow_state)
+{
+	struct kvm_vcpu *shadow_vcpu = &shadow_state->shadow_vcpu;
+
+	if (!shadow_state_is_protected(shadow_state))
+		return;
+
+	/*
+	 * A shadow vcpu has no offset, and sees vtime == ptime. The
+	 * ptimer is fully emulated by EL1 and cannot be trusted.
+	 */
+	write_sysreg(0, cntvoff_el2);
+	isb();
+	write_sysreg_el0(__vcpu_sys_reg(shadow_vcpu, CNTV_CVAL_EL0), SYS_CNTV_CVAL);
+	write_sysreg_el0(__vcpu_sys_reg(shadow_vcpu, CNTV_CTL_EL0), SYS_CNTV_CTL);
+}
+
+static void sync_timer_state(struct kvm_shadow_vcpu_state *shadow_state)
+{
+	struct kvm_vcpu *shadow_vcpu = &shadow_state->shadow_vcpu;
+
+	if (!shadow_state_is_protected(shadow_state))
+		return;
+
+	/*
+	 * Preserve the vtimer state so that it is always correct,
+	 * even if the host tries to make a mess.
+	 */
+	__vcpu_sys_reg(shadow_vcpu, CNTV_CVAL_EL0) = read_sysreg_el0(SYS_CNTV_CVAL);
+	__vcpu_sys_reg(shadow_vcpu, CNTV_CTL_EL0) = read_sysreg_el0(SYS_CNTV_CTL);
+}
+
 static void flush_shadow_state(struct kvm_shadow_vcpu_state *shadow_state)
 {
 	struct kvm_vcpu *shadow_vcpu = &shadow_state->shadow_vcpu;
@@ -85,6 +117,7 @@  static void flush_shadow_state(struct kvm_shadow_vcpu_state *shadow_state)
 	shadow_vcpu->arch.vsesr_el2	= host_vcpu->arch.vsesr_el2;
 
 	flush_vgic_state(host_vcpu, shadow_vcpu);
+	flush_timer_state(shadow_state);
 }
 
 static void sync_shadow_state(struct kvm_shadow_vcpu_state *shadow_state)
@@ -102,6 +135,7 @@  static void sync_shadow_state(struct kvm_shadow_vcpu_state *shadow_state)
 	host_vcpu->arch.flags		= shadow_vcpu->arch.flags;
 
 	sync_vgic_state(host_vcpu, shadow_vcpu);
+	sync_timer_state(shadow_state);
 }
 
 static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt)