[PATCH v2 15/16] KVM: arm64: Populate level on S1PTW SEA injection

[Marc Zyngier <maz@kernel.org>]

Our fault injection mechanism is mildly primitive, and doesn't
really implement the architecture when it comes to reporting
the level of a failing S1 PTW (we blindly report a SEA outside
of a PTW).

Now that we can walk the S1 page tables and look for a particular
IPA in the descriptors, it is pretty easy to improve the SEA
injection code.

Note that we only do it for AArch64 guests, and that 32bit guests
are left to their own device (oddly enough, I don't fancy writing
a 32bit PTW...).

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/inject_fault.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index 6745f38b64f9c..dfcd66c655179 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -106,7 +106,30 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
 {
 	unsigned long cpsr = *vcpu_cpsr(vcpu);
 	bool is_aarch32 = vcpu_mode_is_32bit(vcpu);
-	u64 esr = 0;
+	u64 esr = 0, fsc;
+	int level;
+
+	/*
+	 * If injecting an abort from a failed S1PTW, rewalk the S1 PTs to
+	 * find the failing level. If we can't find it, assume the error was
+	 * transient and restart without changing the state.
+	 */
+	if (kvm_vcpu_abt_iss1tw(vcpu)) {
+		u64 hpfar = kvm_vcpu_get_fault_ipa(vcpu);
+		int ret;
+
+		if (hpfar == INVALID_GPA)
+			return;
+
+		ret = __kvm_find_s1_desc_level(vcpu, addr, hpfar, &level);
+		if (ret)
+			return;
+
+		WARN_ON_ONCE(level < -1 || level > 3);
+		fsc = ESR_ELx_FSC_SEA_TTW(level);
+	} else {
+		fsc = ESR_ELx_FSC_EXTABT;
+	}
 
 	/* This delight is brought to you by FEAT_DoubleFault2. */
 	if (effective_sctlr2_ease(vcpu))
@@ -133,7 +156,7 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
 	if (!is_iabt)
 		esr |= ESR_ELx_EC_DABT_LOW << ESR_ELx_EC_SHIFT;
 
-	esr |= ESR_ELx_FSC_EXTABT;
+	esr |= fsc;
 
 	vcpu_write_sys_reg(vcpu, addr, exception_far_elx(vcpu));
 	vcpu_write_sys_reg(vcpu, esr, exception_esr_elx(vcpu));
-- 
2.39.2