[PATCH 5/6] selftests: KVM: Promote PSCI hypercalls to asm volatile

From: Oliver Upton <oupton@google.com>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Jing Zhang <jingzhangos@google.com>,
	Raghavendra Rao Anata <rananta@google.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Andrew Jones <drjones@redhat.com>,
	Oliver Upton <oupton@google.com>
Subject: [PATCH 5/6] selftests: KVM: Promote PSCI hypercalls to asm volatile
Date: Thu, 19 Aug 2021 22:36:39 +0000	[thread overview]
Message-ID: <20210819223640.3564975-6-oupton@google.com> (raw)
In-Reply-To: <20210819223640.3564975-1-oupton@google.com>

Prevent the compiler from reordering around PSCI hypercalls by promoting
to asm volatile.

Signed-off-by: Oliver Upton <oupton@google.com>
---
 .../selftests/kvm/aarch64/psci_cpu_on_test.c     | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c b/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c
index 018c269990e1..9c22374fc0f5 100644
--- a/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c
+++ b/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c
@@ -31,10 +31,10 @@ static uint64_t psci_cpu_on(uint64_t target_cpu, uint64_t entry_addr,
 	register uint64_t x2 asm("x2") = entry_addr;
 	register uint64_t x3 asm("x3") = context_id;
 
-	asm("hvc #0"
-	    : "=r"(x0)
-	    : "r"(x0), "r"(x1), "r"(x2), "r"(x3)
-	    : "memory");
+	asm volatile("hvc #0"
+		     : "=r"(x0)
+		     : "r"(x0), "r"(x1), "r"(x2), "r"(x3)
+		     : "memory");
 
 	return x0;
 }
@@ -46,10 +46,10 @@ static uint64_t psci_affinity_info(uint64_t target_affinity,
 	register uint64_t x1 asm("x1") = target_affinity;
 	register uint64_t x2 asm("x2") = lowest_affinity_level;
 
-	asm("hvc #0"
-	    : "=r"(x0)
-	    : "r"(x0), "r"(x1), "r"(x2)
-	    : "memory");
+	asm volatile("hvc #0"
+		     : "=r"(x0)
+		     : "r"(x0), "r"(x1), "r"(x2)
+		     : "memory");
 
 	return x0;
 }
-- 
2.33.0.rc2.250.ged5fa647cd-goog

