linux-kernel - [RFC 08/55] KVM: arm64: Set virtual EL2 context depending on the guest exception level

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Date:   Mon,  9 Jan 2017 01:24:04 -0500
From:   Jintack Lim <jintack@...columbia.edu>
To:     christoffer.dall@...aro.org, marc.zyngier@....com,
        pbonzini@...hat.com, rkrcmar@...hat.com, linux@...linux.org.uk,
        catalin.marinas@....com, will.deacon@....com,
        vladimir.murzin@....com, suzuki.poulose@....com,
        mark.rutland@....com, james.morse@....com,
        lorenzo.pieralisi@....com, kevin.brodsky@....com,
        wcohen@...hat.com, shankerd@...eaurora.org, geoff@...radead.org,
        andre.przywara@....com, eric.auger@...hat.com,
        anna-maria@...utronix.de, shihwei@...columbia.edu,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     jintack@...columbia.edu
Subject: [RFC 08/55] KVM: arm64: Set virtual EL2 context depending on the guest exception level

From: Christoffer Dall <christoffer.dall@...aro.org>

Set up virutal EL2 context to hardware if the guest exception level is
EL2.

Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org>
Signed-off-by: Jintack Lim <jintack@...columbia.edu>
---
 arch/arm64/kvm/context.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
index 320afc6..acb4b1e 100644
--- a/arch/arm64/kvm/context.c
+++ b/arch/arm64/kvm/context.c
@@ -25,10 +25,25 @@
 void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
+	if (unlikely(vcpu_mode_el2(vcpu))) {
+		ctxt->hw_pstate = *vcpu_cpsr(vcpu) & ~PSR_MODE_MASK;
 
-	ctxt->hw_pstate = *vcpu_cpsr(vcpu);
-	ctxt->hw_sys_regs = ctxt->sys_regs;
-	ctxt->hw_sp_el1 = ctxt->gp_regs.sp_el1;
+		/*
+		 * We emulate virtual EL2 mode in hardware EL1 mode using the
+		 * same stack pointer mode as the guest expects.
+		 */
+		if ((*vcpu_cpsr(vcpu) & PSR_MODE_MASK) == PSR_MODE_EL2h)
+			ctxt->hw_pstate |= PSR_MODE_EL1h;
+		else
+			ctxt->hw_pstate |= PSR_MODE_EL1t;
+
+		ctxt->hw_sys_regs = ctxt->shadow_sys_regs;
+		ctxt->hw_sp_el1 = ctxt->el2_regs[SP_EL2];
+	} else {
+		ctxt->hw_pstate = *vcpu_cpsr(vcpu);
+		ctxt->hw_sys_regs = ctxt->sys_regs;
+		ctxt->hw_sp_el1 = ctxt->gp_regs.sp_el1;
+	}
 }
 
 /**
@@ -38,9 +53,14 @@ void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
 void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
-
-	*vcpu_cpsr(vcpu) = ctxt->hw_pstate;
-	ctxt->gp_regs.sp_el1 = ctxt->hw_sp_el1;
+	if (unlikely(vcpu_mode_el2(vcpu))) {
+		*vcpu_cpsr(vcpu) &= PSR_MODE_MASK;
+		*vcpu_cpsr(vcpu) |= ctxt->hw_pstate & ~PSR_MODE_MASK;
+		ctxt->el2_regs[SP_EL2] = ctxt->hw_sp_el1;
+	} else {
+		*vcpu_cpsr(vcpu) = ctxt->hw_pstate;
+		ctxt->gp_regs.sp_el1 = ctxt->hw_sp_el1;
+	}
 }
 
 void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt)
-- 
1.9.1