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From:   Andreas Gruenbacher <agruenba@redhat.com>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Paul Mackerras <paulus@ozlabs.org>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        "Darrick J. Wong" <djwong@kernel.org>, Jan Kara <jack@suse.cz>,
        Matthew Wilcox <willy@infradead.org>, cluster-devel@redhat.com,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        ocfs2-devel@oss.oracle.com, kvm-ppc@vger.kernel.org,
        linux-btrfs@vger.kernel.org,
        Andreas Gruenbacher <agruenba@redhat.com>,
        stable@vger.kernel.org
Subject: [PATCH v8 02/17] powerpc/kvm: Fix kvm_use_magic_page
Date:   Tue, 19 Oct 2021 15:41:49 +0200
Message-Id: <20211019134204.3382645-3-agruenba@redhat.com>
In-Reply-To: <20211019134204.3382645-1-agruenba@redhat.com>
References: <20211019134204.3382645-1-agruenba@redhat.com>
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When switching from __get_user to fault_in_pages_readable, commit
9f9eae5ce717 broke kvm_use_magic_page: like __get_user,
fault_in_pages_readable returns 0 on success.

Fixes: 9f9eae5ce717 ("powerpc/kvm: Prefer fault_in_pages_readable function")
Cc: stable@vger.kernel.org # v4.18+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 arch/powerpc/kernel/kvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 617eba82531c..d89cf802d9aa 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -669,7 +669,7 @@ static void __init kvm_use_magic_page(void)
 	on_each_cpu(kvm_map_magic_page, &features, 1);
 
 	/* Quick self-test to see if the mapping works */
-	if (!fault_in_pages_readable((const char *)KVM_MAGIC_PAGE, sizeof(u32))) {
+	if (fault_in_pages_readable((const char *)KVM_MAGIC_PAGE, sizeof(u32))) {
 		kvm_patching_worked = false;
 		return;
 	}
-- 
2.26.3