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Subject[RFC PATCH v2 36/38] KVM: arm64: Respect virtual HCR_EL2.TVM and TRVM settings
Date
Forward the EL1 virtual memory register traps to the virtual EL2 if they
are not coming from the virtual EL2 and the virtual HCR_EL2.TVM or TRVM
bit is set.

This is for recursive nested virtualization.

Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
---
arch/arm64/kvm/sys_regs.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 3559cf7..3e4ec5e 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -135,6 +135,27 @@ static inline bool el12_reg(struct sys_reg_params *p)
return (p->Op1 == 5);
}

+/* This function is to support the recursive nested virtualization */
+static bool forward_vm_traps(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
+{
+ u64 hcr_el2 = vcpu_sys_reg(vcpu, HCR_EL2);
+
+ /* If a trap comes from the virtual EL2, the host hypervisor handles. */
+ if (vcpu_mode_el2(vcpu))
+ return false;
+
+ /*
+ * If the virtual HCR_EL2.TVM or TRVM bit is set, we need to foward
+ * this trap to the virtual EL2.
+ */
+ if ((hcr_el2 & HCR_TVM) && p->is_write)
+ return true;
+ else if ((hcr_el2 & HCR_TRVM) && !p->is_write)
+ return true;
+
+ return false;
+}
+
/*
* Generic accessor for VM registers. Only called as long as HCR_TVM
* is set. If the guest enables the MMU, we stop trapping the VM
@@ -152,6 +173,9 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
if (el12_reg(p) && forward_nv_traps(vcpu))
return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));

+ if (!el12_reg(p) && forward_vm_traps(vcpu, p))
+ return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
+
/*
* Redirect EL1 register accesses to the corresponding EL2 registers if
* they are meant to access EL2 registers.
--
1.9.1
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