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Subject[RFC PATCH v2 37/38] KVM: arm64: Respect the virtual HCR_EL2.NV1 bit setting
Date
Forward ELR_EL1, SPSR_EL1 and VBAR_EL1 traps to the virtual EL2 if the
virtual HCR_EL2.NV bit is set.

This is for recursive nested virtualization.

Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
---
arch/arm64/include/asm/kvm_arm.h | 1 +
arch/arm64/kvm/sys_regs.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index aeaac4e..a1274b7 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -23,6 +23,7 @@
#include <asm/types.h>

/* Hyp Configuration Register (HCR) bits */
+#define HCR_NV1 (UL(1) << 43)
#define HCR_NV (UL(1) << 42)
#define HCR_E2H (UL(1) << 34)
#define HCR_ID (UL(1) << 33)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 3e4ec5e..6f67666 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1031,6 +1031,15 @@ static bool trap_el2_regs(struct kvm_vcpu *vcpu,
return true;
}

+/* This function is to support the recursive nested virtualization */
+static bool forward_nv1_traps(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
+{
+ if (!vcpu_mode_el2(vcpu) && (vcpu_sys_reg(vcpu, HCR_EL2) & HCR_NV1))
+ return true;
+
+ return false;
+}
+
static bool access_elr(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
@@ -1038,6 +1047,9 @@ static bool access_elr(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_nv1_traps(vcpu, p))
+ return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
+
access_rw(p, &vcpu->arch.ctxt.gp_regs.elr_el1);
return true;
}
@@ -1049,6 +1061,9 @@ static bool access_spsr(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_nv1_traps(vcpu, p))
+ return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
+
access_rw(p, &vcpu->arch.ctxt.gp_regs.spsr[KVM_SPSR_EL1]);
return true;
}
@@ -1060,6 +1075,9 @@ static bool access_vbar(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_nv1_traps(vcpu, p))
+ return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
+
access_rw(p, &vcpu_sys_reg(vcpu, r->reg));
return true;
}
--
1.9.1
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