From: Jintack Lim <[email protected]>

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 <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
---
 arch/arm64/include/asm/kvm_arm.h |  1 +
 arch/arm64/kvm/sys_regs.c        | 28 +++++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index c18edb1b35bf..3d2abc40d3a2 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -14,6 +14,7 @@
 /* Hyp Configuration Register (HCR) bits */
 #define HCR_ATA                (UL(1) << 56)
 #define HCR_FWB                (UL(1) << 46)
+#define HCR_NV1                (UL(1) << 43)
 #define HCR_NV         (UL(1) << 42)
 #define HCR_API                (UL(1) << 41)
 #define HCR_APK                (UL(1) << 40)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index d09fda0fd76f..ea511e569ee0 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -299,6 +299,22 @@ static bool access_wi(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)
+{
+       return forward_traps(vcpu, HCR_NV1);
+}
+
+static bool access_vbar_el1(struct kvm_vcpu *vcpu,
+                           struct sys_reg_params *p,
+                           const struct sys_reg_desc *r)
+{
+       if (forward_nv1_traps(vcpu, p))
+               return false;
+
+       return access_rw(vcpu, p, r);
+}
+
 static bool access_sctlr_el2(struct kvm_vcpu *vcpu,
                             struct sys_reg_params *p,
                             const struct sys_reg_desc *r)
@@ -1589,6 +1605,7 @@ static bool access_sp_el1(struct kvm_vcpu *vcpu,
        return true;
 }
 
+
 static bool access_elr(struct kvm_vcpu *vcpu,
                       struct sys_reg_params *p,
                       const struct sys_reg_desc *r)
@@ -1596,6 +1613,9 @@ static bool access_elr(struct kvm_vcpu *vcpu,
        if (el12_reg(p) && forward_nv_traps(vcpu))
                return false;
 
+       if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
+               return false;
+
        if (p->is_write)
                vcpu_write_sys_reg(vcpu, p->regval, ELR_EL1);
        else
@@ -1611,6 +1631,9 @@ static bool access_spsr(struct kvm_vcpu *vcpu,
        if (el12_reg(p) && forward_nv_traps(vcpu))
                return false;
 
+       if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
+               return false;
+
        if (p->is_write)
                __vcpu_sys_reg(vcpu, SPSR_EL1) = p->regval;
        else
@@ -1626,6 +1649,9 @@ static bool access_spsr_el2(struct kvm_vcpu *vcpu,
        if (el12_reg(p) && forward_nv_traps(vcpu))
                return false;
 
+       if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
+               return false;
+
        if (p->is_write)
                vcpu_write_sys_reg(vcpu, p->regval, SPSR_EL2);
        else
@@ -1817,7 +1843,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
        { SYS_DESC(SYS_LORC_EL1), trap_loregion },
        { SYS_DESC(SYS_LORID_EL1), trap_loregion },
 
-       { SYS_DESC(SYS_VBAR_EL1), access_rw, reset_val, VBAR_EL1, 0 },
+       { SYS_DESC(SYS_VBAR_EL1), access_vbar_el1, reset_val, VBAR_EL1, 0 },
        { SYS_DESC(SYS_DISR_EL1), NULL, reset_val, DISR_EL1, 0 },
 
        { SYS_DESC(SYS_ICC_IAR0_EL1), write_to_read_only },
-- 
2.29.2

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