[PATCH 04/14] KVM: arm64: nv: Snapshot S1 ASID tagging information during walk

[Marc Zyngier <maz@kernel.org>]

We currently completely ignore any sort of ASID tagging during a S1
walk, as AT doesn't care about it.

However, such information is required if we are going to create
anything that looks like a TLB from this walk.

Let's capture it both the nG and ASID information while walking
the page tables.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_nested.h |  2 ++
 arch/arm64/kvm/at.c                 | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 43162f1dc4993..2bd315a59f283 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -273,6 +273,8 @@ struct s1_walk_result {
 			u64	pa;
 			s8	level;
 			u8	APTable;
+			bool	nG;
+			u16	asid;
 			bool	UXNTable;
 			bool	PXNTable;
 			bool	uwxn;
diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
index cded013587178..382847ce0c9b7 100644
--- a/arch/arm64/kvm/at.c
+++ b/arch/arm64/kvm/at.c
@@ -410,6 +410,33 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 	wr->pa = desc & GENMASK(47, va_bottom);
 	wr->pa |= va & GENMASK_ULL(va_bottom - 1, 0);
 
+	wr->nG = (wi->regime != TR_EL2) && (desc & PTE_NG);
+	if (wr->nG) {
+		u64 asid_ttbr, tcr;
+
+		switch (wi->regime) {
+		case TR_EL10:
+			tcr = vcpu_read_sys_reg(vcpu, TCR_EL1);
+			asid_ttbr = ((tcr & TCR_A1) ?
+				     vcpu_read_sys_reg(vcpu, TTBR1_EL1) :
+				     vcpu_read_sys_reg(vcpu, TTBR0_EL1));
+			break;
+		case TR_EL20:
+			tcr = vcpu_read_sys_reg(vcpu, TCR_EL2);
+			asid_ttbr = ((tcr & TCR_A1) ?
+				     vcpu_read_sys_reg(vcpu, TTBR1_EL2) :
+				     vcpu_read_sys_reg(vcpu, TTBR0_EL2));
+			break;
+		default:
+			BUG();
+		}
+
+		wr->asid = FIELD_GET(TTBR_ASID_MASK, asid_ttbr);
+		if (!kvm_has_feat_enum(vcpu->kvm, ID_AA64MMFR0_EL1, ASIDBITS, 16) ||
+		    !(tcr & TCR_ASID16))
+			wr->asid &= GENMASK(7, 0);
+	}
+
 	return 0;
 
 addrsz:
-- 
2.39.2