Patch-mainline: v5.3-rc1
Git-commit: a6a6d3b1f867d34ba5bd61aa7bb056b48ca67cff
References: git-fixes
From: Arnd Bergmann <arnd@arndb.de>
Date: Fri, 12 Jul 2019 11:12:30 +0200
Subject: [PATCH] x86: kvm: avoid constant-conversion warning
clang finds a contruct suspicious that converts an unsigned
character to a signed integer and back, causing an overflow:
arch/x86/kvm/mmu.c:4605:39: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -205 to 51 [-Werror,-Wconstant-conversion]
u8 wf = (pfec & PFERR_WRITE_MASK) ? ~w : 0;
~~ ^~
arch/x86/kvm/mmu.c:4607:38: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -241 to 15 [-Werror,-Wconstant-conversion]
u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0;
~~ ^~
arch/x86/kvm/mmu.c:4609:39: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -171 to 85 [-Werror,-Wconstant-conversion]
u8 ff = (pfec & PFERR_FETCH_MASK) ? ~x : 0;
~~ ^~
Add an explicit cast to tell clang that everything works as
intended here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://github.com/ClangBuiltLinux/linux/issues/95
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/x86/kvm/mmu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9a5814d8d194..8f72526e2f68 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4597,11 +4597,11 @@ static void update_permission_bitmask(struct kvm_vcpu *vcpu,
*/
/* Faults from writes to non-writable pages */
- u8 wf = (pfec & PFERR_WRITE_MASK) ? ~w : 0;
+ u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0;
/* Faults from user mode accesses to supervisor pages */
- u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0;
+ u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
/* Faults from fetches of non-executable pages*/
- u8 ff = (pfec & PFERR_FETCH_MASK) ? ~x : 0;
+ u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0;
/* Faults from kernel mode fetches of user pages */
u8 smepf = 0;
/* Faults from kernel mode accesses of user pages */
--
2.35.3