linux-kernel - [PATCH] kvm: avoid uninitialized-variable warnings

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Date:   Thu, 10 Aug 2017 14:14:39 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Michal Hocko <mhocko@...e.com>,
        David Hildenbrand <david@...hat.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Suraj Jitindar Singh <sjitindarsingh@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        Claudio Imbrenda <imbrenda@...ux.vnet.ibm.com>,
        Luiz Capitulino <lcapitulino@...hat.com>,
        Markus Elfring <elfring@...rs.sourceforge.net>,
        "Cao, Lei" <Lei.Cao@...atus.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] kvm: avoid uninitialized-variable warnings

When PAGE_OFFSET is not a compile-time constant, we run into
warnings from the use of kvm_is_error_hva() that the compiler
cannot optimize out:

arch/arm/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_gfn_to_hva_cache_init':
arch/arm/kvm/../../../virt/kvm/kvm_main.c:1978:14: error: 'nr_pages_avail' may be used uninitialized in this function [-Werror=maybe-uninitialized]
arch/arm/kvm/../../../virt/kvm/kvm_main.c: In function 'gfn_to_page_many_atomic':
arch/arm/kvm/../../../virt/kvm/kvm_main.c:1660:5: error: 'entry' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This adds fake initializations to the two instances I ran into.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 virt/kvm/kvm_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 15252d723b54..c812b40dc8de 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1651,7 +1651,7 @@ int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
 			    struct page **pages, int nr_pages)
 {
 	unsigned long addr;
-	gfn_t entry;
+	gfn_t entry = 0;
 
 	addr = gfn_to_hva_many(slot, gfn, &entry);
 	if (kvm_is_error_hva(addr))
@@ -1970,6 +1970,7 @@ static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
 		 * verify that the entire region is valid here.
 		 */
 		while (start_gfn <= end_gfn) {
+			nr_pages_avail = 0;
 			ghc->memslot = __gfn_to_memslot(slots, start_gfn);
 			ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
 						   &nr_pages_avail);
-- 
2.9.0