linux-kernel - [PATCH 5.12 166/173] kvm: fix previous commit for 32-bit builds

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Message-Id: <20210614102703.692179423@linuxfoundation.org>
Date:   Mon, 14 Jun 2021 12:28:18 +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, Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.12 166/173] kvm: fix previous commit for 32-bit builds

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

commit 4422829e8053068e0225e4d0ef42dc41ea7c9ef5 upstream.

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: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/linux/kvm_host.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1124,8 +1124,8 @@ __gfn_to_hva_memslot(struct kvm_memory_s
 	 * 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;
 }