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From: Thomas Huth <thuth@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Laurent Vivier <lvivier@redhat.com>,
	Drew Jones <drjones@redhat.com>, Bill Wendling <morbo@google.com>
Subject: [kvm-unit-tests PATCH 08/11] x86: use a non-negative number in shift
Date: Thu, 14 May 2020 21:26:23 +0200	[thread overview]
Message-ID: <20200514192626.9950-9-thuth@redhat.com> (raw)
In-Reply-To: <20200514192626.9950-1-thuth@redhat.com>

From: Bill Wendling <morbo@google.com>

Shifting a negative number is undefined. Clang complains about it:

x86/svm.c:1131:38: error: shifting a negative signed value is undefined [-Werror,-Wshift-negative-value]
    test->vmcb->control.tsc_offset = TSC_OFFSET_VALUE;

Using "~0ull" results in identical asm code:

	before: movabsq $-281474976710656, %rsi
	after:  movabsq $-281474976710656, %rsi

Signed-off-by: Bill Wendling <morbo@google.com>
[thuth: Rebased to master - code is in svm_tests.c instead of svm.c now]
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 x86/svm_tests.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/x86/svm_tests.c b/x86/svm_tests.c
index 2f53b8f..be1bddf 100644
--- a/x86/svm_tests.c
+++ b/x86/svm_tests.c
@@ -844,7 +844,7 @@ static bool npt_rw_l1mmio_check(struct svm_test *test)
 }
 
 #define TSC_ADJUST_VALUE    (1ll << 32)
-#define TSC_OFFSET_VALUE    (-1ll << 48)
+#define TSC_OFFSET_VALUE    (~0ull << 48)
 static bool ok;
 
 static void tsc_adjust_prepare(struct svm_test *test)
-- 
2.18.1


  parent reply	other threads:[~2020-05-14 19:27 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14 19:26 [kvm-unit-tests PATCH 00/11] Misc fixes and CI improvements Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 01/11] x86/access: Fix phys-bits parameter Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 02/11] Fix out-of-tree builds Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 03/11] x86: avoid multiply defined symbol Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 04/11] Fixes for the umip test Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 05/11] Always compile the kvm-unit-tests with -fno-common Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 06/11] Fix powerpc issue with the linker from Fedora 32 Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 07/11] Update the gitlab-ci to " Thomas Huth
2020-05-14 19:26 ` Thomas Huth [this message]
2020-05-14 19:26 ` [kvm-unit-tests PATCH 09/11] x86: use inline asm to retrieve stack pointer Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 10/11] vmx_tests: Silence warning from Clang Thomas Huth
2020-05-14 19:26 ` [kvm-unit-tests PATCH 11/11] Compile the kvm-unit-tests also with Clang Thomas Huth

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