[RFC 09/55] KVM: arm64: Set shadow EL1 registers for virtual EL2 execution

[Jintack Lim]

From: Christoffer Dall <christoffer.dall at linaro.org>

When entering virtual EL2, we need to reflect virtual EL2 register
states to corresponding shadow EL1 registers. We can simply copy them if
their formats are identical.  Otherwise, we need to convert EL2 register
state to EL1 register state.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Jintack Lim <jintack at cs.columbia.edu>
---
 arch/arm64/kvm/context.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
index acb4b1e..2e9e386 100644
--- a/arch/arm64/kvm/context.c
+++ b/arch/arm64/kvm/context.c
@@ -17,6 +17,76 @@
 
 #include <linux/kvm_host.h>
 #include <asm/kvm_emulate.h>
+#include <asm/esr.h>
+
+struct el1_el2_map {
+	enum vcpu_sysreg	el1;
+	enum el2_regs		el2;
+};
+
+/*
+ * List of EL2 registers which can be directly applied to EL1 registers to
+ * emulate running EL2 in EL1.  The EL1 registers here must either be trapped
+ * or paravirtualized in EL1.
+ */
+static const struct el1_el2_map el1_el2_map[] = {
+	{ AMAIR_EL1, AMAIR_EL2 },
+	{ MAIR_EL1, MAIR_EL2 },
+	{ TTBR0_EL1, TTBR0_EL2 },
+	{ ACTLR_EL1, ACTLR_EL2 },
+	{ AFSR0_EL1, AFSR0_EL2 },
+	{ AFSR1_EL1, AFSR1_EL2 },
+	{ SCTLR_EL1, SCTLR_EL2 },
+	{ VBAR_EL1, VBAR_EL2 },
+};
+
+static inline u64 tcr_el2_ips_to_tcr_el1_ps(u64 tcr_el2)
+{
+	return ((tcr_el2 & TCR_EL2_PS_MASK) >> TCR_EL2_PS_SHIFT)
+		<< TCR_IPS_SHIFT;
+}
+
+static inline u64 cptr_el2_to_cpacr_el1(u64 cptr_el2)
+{
+	u64 cpacr_el1 = 0;
+
+	if (!(cptr_el2 & CPTR_EL2_TFP))
+		cpacr_el1 |= CPACR_EL1_FPEN;
+	if (cptr_el2 & CPTR_EL2_TTA)
+		cpacr_el1 |= CPACR_EL1_TTA;
+
+	return cpacr_el1;
+}
+
+static void create_shadow_el1_sysregs(struct kvm_vcpu *vcpu)
+{
+	u64 *s_sys_regs = vcpu->arch.ctxt.shadow_sys_regs;
+	u64 *el2_regs = vcpu->arch.ctxt.el2_regs;
+	u64 tcr_el2;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(el1_el2_map); i++) {
+		const struct el1_el2_map *map = &el1_el2_map[i];
+
+		s_sys_regs[map->el1] = el2_regs[map->el2];
+	}
+
+	tcr_el2 = el2_regs[TCR_EL2];
+	s_sys_regs[TCR_EL1] =
+		TCR_EPD1 |	/* disable TTBR1_EL1 */
+		((tcr_el2 & TCR_EL2_TBI) ? TCR_TBI0 : 0) |
+		tcr_el2_ips_to_tcr_el1_ps(tcr_el2) |
+		(tcr_el2 & TCR_EL2_TG0_MASK) |
+		(tcr_el2 & TCR_EL2_ORGN0_MASK) |
+		(tcr_el2 & TCR_EL2_IRGN0_MASK) |
+		(tcr_el2 & TCR_EL2_T0SZ_MASK);
+
+	/* Rely on separate VMID for VA context, always use ASID 0 */
+	s_sys_regs[TTBR0_EL1] &= ~GENMASK_ULL(63, 48);
+	s_sys_regs[TTBR1_EL1] = 0;
+
+	s_sys_regs[CPACR_EL1] = cptr_el2_to_cpacr_el1(el2_regs[CPTR_EL2]);
+}
 
 /**
  * kvm_arm_setup_shadow_state -- prepare shadow state based on emulated mode
@@ -37,6 +107,7 @@ void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
 		else
 			ctxt->hw_pstate |= PSR_MODE_EL1t;
 
+		create_shadow_el1_sysregs(vcpu);
 		ctxt->hw_sys_regs = ctxt->shadow_sys_regs;
 		ctxt->hw_sp_el1 = ctxt->el2_regs[SP_EL2];
 	} else {
-- 
1.9.1