Subject: [PATCH v5 17/69] KVM: arm64: nv: Add non-VHE-EL2->EL1 translation helpers

From: Marc Zyngier <[email-masked]>
Date: Mon, 29 Nov 2021 20:00:58 +0000

Some EL2 system registers immediately affect the current execution
of the system, so we need to use their respective EL1 counterparts.
For this we need to define a mapping between the two. In general,
this only affects non-VHE guest hypervisors, as VHE system registers
are compatible with the EL1 counterparts.

These helpers will get used in subsequent patches.

Co-developed-by: Andre Przywara <[email-masked]>
Signed-off-by: Andre Przywara <[email-masked]>
Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/include/asm/kvm_nested.h | 50 +++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 1028ac65a897..67a2c0d05233 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -2,6 +2,7 @@
 #ifndef __ARM64_KVM_NESTED_H
 #define __ARM64_KVM_NESTED_H
 
+#include <linux/bitfield.h>
 #include <linux/kvm_host.h>
 
 static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu)
@@ -11,4 +12,53 @@ static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu)
 		test_bit(KVM_ARM_VCPU_HAS_EL2, vcpu->arch.features));
 }
 
+/* Translation helpers from non-VHE EL2 to EL1 */
+static inline u64 tcr_el2_ips_to_tcr_el1_ps(u64 tcr_el2)
+{
+	return (u64)FIELD_GET(TCR_EL2_PS_MASK, tcr_el2) << TCR_IPS_SHIFT;
+}
+
+static inline u64 translate_tcr_el2_to_tcr_el1(u64 tcr)
+{
+	return TCR_EPD1_MASK |				/* disable TTBR1_EL1 */
+	       ((tcr & TCR_EL2_TBI) ? TCR_TBI0 : 0) |
+	       tcr_el2_ips_to_tcr_el1_ps(tcr) |
+	       (tcr & TCR_EL2_TG0_MASK) |
+	       (tcr & TCR_EL2_ORGN0_MASK) |
+	       (tcr & TCR_EL2_IRGN0_MASK) |
+	       (tcr & TCR_EL2_T0SZ_MASK);
+}
+
+static inline u64 translate_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;
+	if (!(cptr_el2 & CPTR_EL2_TZ))
+		cpacr_el1 |= CPACR_EL1_ZEN;
+
+	return cpacr_el1;
+}
+
+static inline u64 translate_sctlr_el2_to_sctlr_el1(u64 sctlr)
+{
+	/* Bit 20 is RES1 in SCTLR_EL1, but RES0 in SCTLR_EL2 */
+	return sctlr | BIT(20);
+}
+
+static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0)
+{
+	/* Force ASID to 0 (ASID 0 or RES0) */
+	return ttbr0 & ~GENMASK_ULL(63, 48);
+}
+
+static inline u64 translate_cnthctl_el2_to_cntkctl_el1(u64 cnthctl)
+{
+	return ((FIELD_GET(CNTHCTL_EL1PCTEN | CNTHCTL_EL1PCEN, cnthctl) << 10) |
+		(cnthctl & (CNTHCTL_EVNTI | CNTHCTL_EVNTDIR | CNTHCTL_EVNTEN)));
+}
+
 #endif /* __ARM64_KVM_NESTED_H */
-- 
2.30.2

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