linux-kernel - [PATCH 4.9 046/104] infiniband: Fix alignment of mmap cookies to support VIPT caching

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Date:   Fri, 22 Dec 2017 09:46:12 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Josh Beavers <josh.beavers@...il.com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Doug Ledford <dledford@...hat.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 046/104] infiniband: Fix alignment of mmap cookies to support VIPT caching

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Gunthorpe <jgunthorpe@...idianresearch.com>


[ Upstream commit cb8864559631754ac93d5734b165ccd0cad4728c ]

When vmalloc_user is used to create memory that is supposed to be mmap'd
to user space, it is necessary for the mmap cookie (eg the offset) to be
aligned to SHMLBA.

This creates a situation where all virtual mappings of the same physical
page share the same virtual cache index and guarantees VIPT coherence.
Otherwise the cache is non-coherent and the kernel will not see writes
by userspace when reading the shared page (or vice-versa).

Reported-by: Josh Beavers <josh.beavers@...il.com>
Signed-off-by: Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/infiniband/sw/rdmavt/mmap.c  |    4 ++--
 drivers/infiniband/sw/rxe/rxe_mmap.c |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/infiniband/sw/rdmavt/mmap.c
+++ b/drivers/infiniband/sw/rdmavt/mmap.c
@@ -170,9 +170,9 @@ struct rvt_mmap_info *rvt_create_mmap_in
 
 	spin_lock_irq(&rdi->mmap_offset_lock);
 	if (rdi->mmap_offset == 0)
-		rdi->mmap_offset = PAGE_SIZE;
+		rdi->mmap_offset = ALIGN(PAGE_SIZE, SHMLBA);
 	ip->offset = rdi->mmap_offset;
-	rdi->mmap_offset += size;
+	rdi->mmap_offset += ALIGN(size, SHMLBA);
 	spin_unlock_irq(&rdi->mmap_offset_lock);
 
 	INIT_LIST_HEAD(&ip->pending_mmaps);
--- a/drivers/infiniband/sw/rxe/rxe_mmap.c
+++ b/drivers/infiniband/sw/rxe/rxe_mmap.c
@@ -156,10 +156,10 @@ struct rxe_mmap_info *rxe_create_mmap_in
 	spin_lock_bh(&rxe->mmap_offset_lock);
 
 	if (rxe->mmap_offset == 0)
-		rxe->mmap_offset = PAGE_SIZE;
+		rxe->mmap_offset = ALIGN(PAGE_SIZE, SHMLBA);
 
 	ip->info.offset = rxe->mmap_offset;
-	rxe->mmap_offset += size;
+	rxe->mmap_offset += ALIGN(size, SHMLBA);
 
 	spin_unlock_bh(&rxe->mmap_offset_lock);