From 2691f0ff3d96b471a69c7ef29f3340b91056845d Mon Sep 17 00:00:00 2001
From: Alexey Kardashevskiy <aik@ozlabs.ru>
Date: Mon, 10 Sep 2018 18:29:11 +1000
Subject: [PATCH] KVM: PPC: Propagate errors to the guest when failed instead
 of ignoring

References: bsc#1061840 git-fixes
Patch-mainline: v4.20-rc1
Git-commit: 2691f0ff3d96b471a69c7ef29f3340b91056845d

At the moment if the PUT_TCE{_INDIRECT} handlers fail to update
the hardware tables, we print a warning once, clear the entry and
continue. This is so as at the time the assumption was that if
a VFIO device is hotplugged into the guest, and the userspace replays
virtual DMA mappings (i.e. TCEs) to the hardware tables and if this fails,
then there is nothing useful we can do about it.

However the assumption is not valid as these handlers are not called for
TCE replay (VFIO ioctl interface is used for that) and these handlers
are for new TCEs.

This returns an error to the guest if there is a request which cannot be
processed. By now the only possible failure must be H_TOO_HARD.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kvm/book3s_64_vio.c    | 20 ++++++--------------
 arch/powerpc/kvm/book3s_64_vio_hv.c | 21 +++++++--------------
 2 files changed, 13 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index 01e1994daff0..8231b178eac6 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -568,14 +568,10 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
 			ret = kvmppc_tce_iommu_map(vcpu->kvm, stt, stit->tbl,
 					entry, ua, dir);
 
-		if (ret == H_SUCCESS)
-			continue;
-
-		if (ret == H_TOO_HARD)
+		if (ret != H_SUCCESS) {
+			kvmppc_clear_tce(stit->tbl, entry);
 			goto unlock_exit;
-
-		WARN_ON_ONCE(1);
-		kvmppc_clear_tce(stit->tbl, entry);
+		}
 	}
 
 	kvmppc_tce_put(stt, entry, tce);
@@ -663,14 +659,10 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
 					stit->tbl, entry + i, ua,
 					iommu_tce_direction(tce));
 
-			if (ret == H_SUCCESS)
-				continue;
-
-			if (ret == H_TOO_HARD)
+			if (ret != H_SUCCESS) {
+				kvmppc_clear_tce(stit->tbl, entry);
 				goto unlock_exit;
-
-			WARN_ON_ONCE(1);
-			kvmppc_clear_tce(stit->tbl, entry);
+			}
 		}
 
 		kvmppc_tce_put(stt, entry + i, tce);
diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
index 3c05fc22de07..ae147b5c7571 100644
--- a/arch/powerpc/kvm/book3s_64_vio_hv.c
+++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
@@ -405,14 +405,10 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
 			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm, stt,
 					stit->tbl, entry, ua, dir);
 
-		if (ret == H_SUCCESS)
-			continue;
-
-		if (ret == H_TOO_HARD)
+		if (ret != H_SUCCESS) {
+			kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl, entry);
 			return ret;
-
-		WARN_ON_ONCE_RM(1);
-		kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl, entry);
+		}
 	}
 
 	kvmppc_tce_put(stt, entry, tce);
@@ -558,14 +554,11 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
 					stit->tbl, entry + i, ua,
 					iommu_tce_direction(tce));
 
-			if (ret == H_SUCCESS)
-				continue;
-
-			if (ret == H_TOO_HARD)
+			if (ret != H_SUCCESS) {
+				kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl,
+						entry);
 				goto unlock_exit;
-
-			WARN_ON_ONCE_RM(1);
-			kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl, entry);
+			}
 		}
 
 		kvmppc_tce_put(stt, entry + i, tce);
-- 
2.35.3