linux-kernel - [PATCH 5.6 048/126] iommu/amd: Do not loop forever when trying to increase address space

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Message-Id: <20200526183942.060883968@linuxfoundation.org>
Date:   Tue, 26 May 2020 20:53:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
        Qian Cai <cai@....pw>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.6 048/126] iommu/amd: Do not loop forever when trying to increase address space

From: Joerg Roedel <jroedel@...e.de>

[ Upstream commit 5b8a9a047b6cad361405c7900c1e1cdd378c4589 ]

When increase_address_space() fails to allocate memory, alloc_pte()
will call it again until it succeeds. Do not loop forever while trying
to increase the address space and just return an error instead.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Tested-by: Qian Cai <cai@....pw>
Link: https://lore.kernel.org/r/20200504125413.16798-3-joro@8bytes.org
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/amd_iommu.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 1d8634250afc..18c995a16d80 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1500,8 +1500,19 @@ static u64 *alloc_pte(struct protection_domain *domain,
 	amd_iommu_domain_get_pgtable(domain, &pgtable);
 
 	while (address > PM_LEVEL_SIZE(pgtable.mode)) {
-		*updated = increase_address_space(domain, address, gfp) || *updated;
+		bool upd = increase_address_space(domain, address, gfp);
+
+		/* Read new values to check if update was successful */
 		amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+		/*
+		 * Return an error if there is no memory to update the
+		 * page-table.
+		 */
+		if (!upd && (address > PM_LEVEL_SIZE(pgtable.mode)))
+			return NULL;
+
+		*updated = *updated || upd;
 	}
 
 
-- 
2.25.1