KVM: arm64: nv: Add non-VHE-EL2->EL1 translation helpers

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.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Co-developed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 249b03fc2ccee86d9534b872f9201ec558a24d40..4882905357f43b6b5146f5d4f38d13b100f8dbb8 100644 (file)
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -2,8 +2,9 @@
 #ifndef __ARM64_KVM_NESTED_H
 #define __ARM64_KVM_NESTED_H
 
-#include <asm/kvm_emulate.h>
+#include <linux/bitfield.h>
 #include <linux/kvm_host.h>
+#include <asm/kvm_emulate.h>
 
 static inline bool vcpu_has_nv(const struct kvm_vcpu *vcpu)
 {
@@ -12,6 +13,53 @@ static inline bool vcpu_has_nv(const struct kvm_vcpu *vcpu)
                vcpu_has_feature(vcpu, KVM_ARM_VCPU_HAS_EL2));
 }
 
+/* Translation helpers from non-VHE EL2 to EL1 */
+static inline u64 tcr_el2_ps_to_tcr_el1_ips(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_ps_to_tcr_el1_ips(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_TTA)
+               cpacr_el1 |= CPACR_ELx_TTA;
+       if (!(cptr_el2 & CPTR_EL2_TFP))
+               cpacr_el1 |= CPACR_ELx_FPEN;
+       if (!(cptr_el2 & CPTR_EL2_TZ))
+               cpacr_el1 |= CPACR_ELx_ZEN;
+
+       return cpacr_el1;
+}
+
+static inline u64 translate_sctlr_el2_to_sctlr_el1(u64 val)
+{
+       /* Only preserve the minimal set of bits we support */
+       val &= (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | SCTLR_ELx_SA |
+               SCTLR_ELx_I | SCTLR_ELx_IESB | SCTLR_ELx_WXN | SCTLR_ELx_EE);
+       val |= SCTLR_EL1_RES1;
+
+       return val;
+}
+
+static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0)
+{
+       /* Clear the ASID field */
+       return ttbr0 & ~GENMASK_ULL(63, 48);
+}
+
 extern bool __check_nv_sr_forward(struct kvm_vcpu *vcpu);
 
 int kvm_init_nv_sysregs(struct kvm *kvm);