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KVM: selftests: Mark "guest_saw_irq" as volatile in xen_shinfo_test

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Tag "guest_saw_irq" as "volatile" to ensure that the compiler will never
optimize away lookups.  Relying on the compiler thinking that the flag
is global and thus might change also works, but it's subtle, less robust,
and looks like a bug at first glance, e.g. risks being "fixed" and
breaking the test.

Make the flag "static" as well since convincing the compiler it's global
is no longer necessary.

Alternatively, the flag could be accessed with {READ,WRITE}_ONCE(), but
literally every access would need the wrappers, and eking out performance
isn't exactly top priority for selftests.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221013211234.1318131-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-10-13 21:12:34 +00:00 committed by Paolo Bonzini
parent a51abbbf25
commit 5addaf5309
1 changed files with 1 additions and 1 deletions
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2
tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
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@ -132,7 +132,7 @@ struct {
struct kvm_irq_routing_entry entries[2];
} irq_routes;
bool guest_saw_irq;
static volatile bool guest_saw_irq;
static void evtchn_handler(struct ex_regs *regs)
{