Commit 99bc6753 authored Aug 29, 2016 by Juergen Gross Committed by Ingo Molnar Sep 05, 2016

xen: Add xen_pin_vcpu() to support calling functions on a dedicated pCPU



Some hardware models (e.g. Dell Studio 1555 laptops) require calls to
the firmware to be issued on CPU 0 only. As Dom0 might have to use
these calls, add xen_pin_vcpu() to achieve this functionality.

In case either the domain doesn't have the privilege to make the
related hypercall or the hypervisor isn't supporting it, issue a
warning once and disable further pinning attempts.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David Vrabel <david.vrabel@citrix.com>
Cc: Douglas_Warzecha@dell.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: chrisw@sous-sol.org
Cc: hpa@zytor.com
Cc: jdelvare@suse.com
Cc: jeremy@goop.org
Cc: linux@roeck-us.net
Cc: pali.rohar@gmail.com
Cc: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1472453327-19050-5-git-send-email-jgross@suse.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent df8ce9d7

arch/x86/xen/enlighten.c

+40 −0

Original line number	Diff line number	Diff line
		@@ -1925,6 +1925,45 @@ static void xen_set_cpu_features(struct cpuinfo_x86 *c)
		}
		}

		static void xen_pin_vcpu(int cpu)
		{
		static bool disable_pinning;
		struct sched_pin_override pin_override;
		int ret;

		if (disable_pinning)
		return;

		pin_override.pcpu = cpu;
		ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);

		/* Ignore errors when removing override. */
		if (cpu < 0)
		return;

		switch (ret) {
		case -ENOSYS:
		pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
		cpu);
		disable_pinning = true;
		break;
		case -EPERM:
		WARN(1, "Trying to pin vcpu without having privilege to do so\n");
		disable_pinning = true;
		break;
		case -EINVAL:
		case -EBUSY:
		pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
		cpu);
		break;
		case 0:
		break;
		default:
		WARN(1, "rc %d while trying to pin vcpu\n", ret);
		disable_pinning = true;
		}
		}

		const struct hypervisor_x86 x86_hyper_xen = {
		.name = "Xen",
		.detect = xen_platform,
		@@ -1933,6 +1972,7 @@ const struct hypervisor_x86 x86_hyper_xen = {
		#endif
		.x2apic_available = xen_x2apic_para_available,
		.set_cpu_features = xen_set_cpu_features,
		.pin_vcpu = xen_pin_vcpu,
		};
		EXPORT_SYMBOL(x86_hyper_xen);

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