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From: Andrei Dulea via iommu <iommu@lists.linux-foundation.org>
To: Joerg Roedel <joro@8bytes.org>
Cc: iommu@lists.linux-foundation.org,
	"Jan H. Schönherr" <jschoenh@amazon.de>,
	"Andrei Dulea" <adulea@amazon.de>
Subject: [PATCH 2/4] iommu/amd: Fix downgrading default page-sizes in alloc_pte()
Date: Fri, 13 Sep 2019 16:42:29 +0200
Message-ID: <20190913144231.21382-3-adulea@amazon.de> (raw)
In-Reply-To: <20190913144231.21382-1-adulea@amazon.de>

Downgrading an existing large mapping to a mapping using smaller
page-sizes works only for the mappings created with page-mode 7 (i.e.
non-default page size).

Treat large mappings created with page-mode 0 (i.e. default page size)
like a non-present mapping and allow to overwrite it in alloc_pte().

While around, make sure that we flush the TLB only if we change an
existing mapping, otherwise we might end up acting on garbage PTEs.

Signed-off-by: Andrei Dulea <adulea@amazon.de>
---
 drivers/iommu/amd_iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 138547446345..c7e28a8d25d1 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1490,6 +1490,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
 		pte_level = PM_PTE_LEVEL(__pte);
 
 		if (!IOMMU_PTE_PRESENT(__pte) ||
+		    pte_level == PAGE_MODE_NONE ||
 		    pte_level == PAGE_MODE_7_LEVEL) {
 			page = (u64 *)get_zeroed_page(gfp);
 			if (!page)
@@ -1500,7 +1501,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
 			/* pte could have been changed somewhere. */
 			if (cmpxchg64(pte, __pte, __npte) != __pte)
 				free_page((unsigned long)page);
-			else if (pte_level == PAGE_MODE_7_LEVEL)
+			else if (IOMMU_PTE_PRESENT(__pte))
 				domain->updated = true;
 
 			continue;
-- 
2.17.1

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  parent reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 14:42 [PATCH 0/4] iommu/amd: re-mapping fixes Andrei Dulea via iommu
2019-09-13 14:42 ` [PATCH 1/4] iommu/amd: Fix pages leak in free_pagetable() Andrei Dulea via iommu
2019-09-13 14:42 ` Andrei Dulea via iommu [this message]
2019-09-13 14:42 ` [PATCH 3/4] iommu/amd: Introduce first_pte_l7() helper Andrei Dulea via iommu
2019-09-13 14:42 ` [PATCH 4/4] iommu/amd: Unmap all L7 PTEs when downgrading page-sizes Andrei Dulea via iommu

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