[PATCH v4 07/13] KVM: s390: Return -EINTR if a signal was pending while faulting-in

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

If a signal is pending while trying to fault-in a page, return -EINTR
instead of -EAGAIN.

Also fix unpack_one() and handle_mvpg_pei() so that they can handle
-EINTR properly.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Fixes: e907ae530133 ("KVM: s390: Add helper functions for fault handling")
---
 arch/s390/kvm/faultin.c   |  4 ++--
 arch/s390/kvm/intercept.c | 23 +++++++++++++----------
 arch/s390/kvm/pv.c        |  2 +-
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/arch/s390/kvm/faultin.c b/arch/s390/kvm/faultin.c
index fee80047bd94..4ff4c5970956 100644
--- a/arch/s390/kvm/faultin.c
+++ b/arch/s390/kvm/faultin.c
@@ -92,8 +92,8 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa
 		if (is_noslot_pfn(f->pfn))
 			return PGM_ADDRESSING;
 		/* Signal pending: try again. */
-		if (f->pfn == KVM_PFN_ERR_SIGPENDING)
-			return -EAGAIN;
+		if (is_sigpending_pfn(f->pfn))
+			return -EINTR;
 		/* Check if it's read-only memory; don't try to actually handle that case. */
 		if (f->pfn == KVM_PFN_ERR_RO_FAULT)
 			return -EOPNOTSUPP;
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 1980df61ef30..a40fe2a10cbf 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -369,27 +369,30 @@ static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
 	if (rc)
 		return kvm_s390_inject_prog_cond(vcpu, rc);
 
-	do {
-		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(srcaddr), false);
-	} while (rc == -EAGAIN);
-	if (rc)
-		return rc;
-
-	/* Ensure that the source is paged-in, no actual access -> no key checking */
+	/* Ensure that the destination is paged-in, no actual access -> no key checking */
 	rc = guest_translate_address_with_key(vcpu, vcpu->run->s.regs.gprs[reg1],
 					      reg1, &dstaddr, GACC_STORE, 0);
 	if (rc)
 		return kvm_s390_inject_prog_cond(vcpu, rc);
 
+	/*
+	 * If an error happens below, the instruction needs to be retried.
+	 * Positive error codes are impossible; addressing exceptions would
+	 * have been discovered and reported above.
+	 */
+	kvm_s390_retry_instr(vcpu);
+
 	do {
-		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(dstaddr), true);
+		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(srcaddr), false);
 	} while (rc == -EAGAIN);
 	if (rc)
 		return rc;
 
-	kvm_s390_retry_instr(vcpu);
+	do {
+		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(dstaddr), true);
+	} while (rc == -EAGAIN);
 
-	return 0;
+	return rc;
 }
 
 static int handle_partial_execution(struct kvm_vcpu *vcpu)
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 1beacc841ca8..dc204b521052 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -809,7 +809,7 @@ static int unpack_one(struct kvm *kvm, unsigned long addr, u64 tweak,
 			return -EAGAIN;
 	}
 
-	if (ret && ret != -EAGAIN)
+	if (ret && ret != -EAGAIN && ret != -EINTR)
 		KVM_UV_EVENT(kvm, 3, "PROTVIRT VM UNPACK: failed addr %llx with rc %x rrc %x",
 			     uvcb.gaddr, *rc, *rrc);
 	return ret;
-- 
2.55.0