[RFC PATCH v1 1/5] arm64: Add TLB Conflict Abort Exception handler to KVM

["Mikołaj Lenczewski" <miko.lenczewski@arm.com>]

Currently, KVM does not handle the case of a stage 2 TLB conflict abort
exception. The Arm ARM specifies that the worst-case handling of such an
exception requires a `tlbi vmalls12e1`. Perform such an invalidation
when this exception is encountered.

Signed-off-by: Mikołaj Lenczewski <miko.lenczewski@arm.com>
---
 arch/arm64/include/asm/esr.h | 8 ++++++++
 arch/arm64/kvm/mmu.c         | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index d1b1a33f9a8b..8a66f81ca291 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -121,6 +121,7 @@
 #define ESR_ELx_FSC_SEA_TTW(n)	(0x14 + (n))
 #define ESR_ELx_FSC_SECC	(0x18)
 #define ESR_ELx_FSC_SECC_TTW(n)	(0x1c + (n))
+#define ESR_ELx_FSC_TLBABT	(0x30)
 
 /* Status codes for individual page table levels */
 #define ESR_ELx_FSC_ACCESS_L(n)	(ESR_ELx_FSC_ACCESS + (n))
@@ -464,6 +465,13 @@ static inline bool esr_fsc_is_access_flag_fault(unsigned long esr)
 	       (esr == ESR_ELx_FSC_ACCESS_L(0));
 }
 
+static inline bool esr_fsc_is_tlb_conflict_abort(unsigned long esr)
+{
+	esr = esr & ESR_ELx_FSC;
+
+	return esr == ESR_ELx_FSC_TLBABT;
+}
+
 /* Indicate whether ESR.EC==0x1A is for an ERETAx instruction */
 static inline bool esr_iss_is_eretax(unsigned long esr)
 {
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index c9d46ad57e52..c8c6f5a97a1b 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1756,6 +1756,12 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 	ipa = fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
 	is_iabt = kvm_vcpu_trap_is_iabt(vcpu);
 
+	if (esr_fsc_is_tlb_conflict_abort(esr)) {
+		// does a `tlbi vmalls12e1is`
+		__kvm_tlb_flush_vmid(&vcpu->kvm->arch.mmu);
+		return 1;
+	}
+
 	if (esr_fsc_is_translation_fault(esr)) {
 		/* Beyond sanitised PARange (which is the IPA limit) */
 		if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) {
-- 
2.45.2