linux-kernel - [PATCH AUTOSEL 5.4 14/15] kvm: fix previous commit for 32-bit builds

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Message-Id: <20210615154948.62711-14-sashal@kernel.org>
Date:   Tue, 15 Jun 2021 11:49:46 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>, kvm@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 14/15] kvm: fix previous commit for 32-bit builds

From: Paolo Bonzini <pbonzini@...hat.com>

[ Upstream commit 4422829e8053068e0225e4d0ef42dc41ea7c9ef5 ]

array_index_nospec does not work for uint64_t on 32-bit builds.
However, the size of a memory slot must be less than 20 bits wide
on those system, since the memory slot must fit in the user
address space.  So just store it in an unsigned long.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/kvm_host.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6c29afb76070..a1ff6b76aa8c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1051,8 +1051,8 @@ __gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
 	 * table walks, do not let the processor speculate loads outside
 	 * the guest's registered memslots.
 	 */
-	unsigned long offset = array_index_nospec(gfn - slot->base_gfn,
-						  slot->npages);
+	unsigned long offset = gfn - slot->base_gfn;
+	offset = array_index_nospec(offset, slot->npages);
 	return slot->userspace_addr + offset * PAGE_SIZE;
 }
 
-- 
2.30.2