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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1/2] Xen acpi pad implement
On Mon, Oct 29, 2012 at 03:38:14AM +0000, Liu, Jinsong wrote:
> It's doable to register a stub for xen. However, it's not preferred, say, to
> make xen pad as module, considering the case 'rmmod xen_acpi_pad' then
> 'insmod acpi_pad'? Under such case there is risk of mwait #UD, if we want to
> remove mwait check as 'patch 2/2:
> Revert-pad-config-check-in-xen_check_mwait.patch' did, advantages of which is
> to enjoy deep Cx.
You are missing my point. This is what I was thinking off:
>From 5f30320b8a1c21d60a2c22e98bcf013b7773938b Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Mon, 29 Oct 2012 08:38:22 -0400
Subject: [PATCH] xen/acpi: Provide a stub function to register for ACPI PAD
module.
TODO: Give more details.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
drivers/xen/Kconfig | 5 ++
drivers/xen/Makefile | 3 +-
drivers/xen/xen-acpi-pad-stub.c | 128 +++++++++++++++++++++++++++++++++++++++
drivers/xen/xen-acpi.h | 2 +
4 files changed, 137 insertions(+), 1 deletions(-)
create mode 100644 drivers/xen/xen-acpi-pad-stub.c
create mode 100644 drivers/xen/xen-acpi.h
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index d4dffcd..9156a08 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -204,4 +204,9 @@ config XEN_MCE_LOG
Allow kernel fetching MCE error from Xen platform and
converting it into Linux mcelog format for mcelog tools
+config XEN_ACPI_PAD_STUB
+ bool
+ depends on XEN_DOM0 && X86_64 && ACPI
+ default n
+
endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 0e863703..d1895d9 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -9,9 +9,10 @@ nostackp := $(call cc-option, -fno-stack-protector)
CFLAGS_features.o := $(nostackp)
dom0-$(CONFIG_PCI) += pci.o
-dom0-$(CONFIG_USB_SUPPORT) += dbgp.o
+dom0-$(CONFIG_USB_EHCI_HCD) += dbgp.o
dom0-$(CONFIG_ACPI) += acpi.o
dom0-$(CONFIG_X86) += pcpu.o
+dom0-$(CONFIG_XEN_ACPI_PAD_STUB) += xen-acpi-pad-stub.o
obj-$(CONFIG_XEN_DOM0) += $(dom0-y)
obj-$(CONFIG_BLOCK) += biomerge.o
obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
diff --git a/drivers/xen/xen-acpi-pad-stub.c b/drivers/xen/xen-acpi-pad-stub.c
new file mode 100644
index 0000000..cac9a39
--- /dev/null
+++ b/drivers/xen/xen-acpi-pad-stub.c
@@ -0,0 +1,128 @@
+/*
+ * Copyright 2012 by Oracle Inc
+ * Author: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
+ *
+ * This code borrows ideas from https://lkml.org/lkml/2011/11/30/249
+ * so many thanks go to Kevin Tian <kevin.tian@xxxxxxxxx>
+ * and Yu Ke <ke.yu@xxxxxxxxx>.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/cpumask.h>
+#include <linux/freezer.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+#include <acpi/processor.h>
+
+#include <xen/xen.h>
+#include <xen/interface/platform.h>
+#include <xen/interface/version.h>
+#include <asm/xen/hypercall.h>
+
+/* TODO: Needs comments. */
+static struct acpi_device_ops *xen_acpi_pad_ops;
+static bool __read_mostly xen_acpi_pad_registered;
+static DEFINE_SPINLOCK(xen_acpi_pad_spinlock);
+
+int xen_register_acpi_pad_owner(struct acpi_device_ops *ops)
+{
+ if (xen_acpi_pad_ops)
+ return -EEXIST;
+
+ spin_lock(&xen_acpi_pad_spinlock);
+ xen_acpi_pad_ops = ops;
+ spin_unlock(&xen_acpi_pad_spinlock);
+ return 0;
+}
+int xen_unregister_acpi_pad_owner(struct acpi_device_ops *ops)
+{
+ spin_lock(&xen_acpi_pad_spinlock);
+ if (xen_acpi_pad_ops != ops) {
+ spin_unlock(&xen_acpi_pad_spinlock);
+ return -ENODEV;
+ }
+ xen_acpi_pad_ops = NULL;
+ spin_unlock(&xen_acpi_pad_spinlock);
+ return 0;
+}
+
+static int xen_acpi_pad_remove(struct acpi_device *device, int type)
+{
+ int ret = -ENOSYS;
+
+ spin_lock(&xen_acpi_pad_spinlock);
+ if (xen_acpi_pad_ops && xen_acpi_pad_ops->remove)
+ ret = xen_acpi_pad_ops->remove(device, type);
+ spin_unlock(&xen_acpi_pad_spinlock);
+ return ret;
+}
+static int xen_acpi_pad_add(struct acpi_device *device)
+{
+ int ret = -ENOSYS;
+ spin_lock(&xen_acpi_pad_spinlock);
+ if (xen_acpi_pad_ops && xen_acpi_pad_ops->add)
+ ret = xen_acpi_pad_ops->add(device);
+ spin_unlock(&xen_acpi_pad_spinlock);
+ return ret;
+}
+
+static const struct acpi_device_id pad_device_ids[] = {
+ {"ACPI000C", 0},
+ {"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, pad_device_ids);
+#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
+
+static struct acpi_driver xen_acpi_pad_driver = {
+ .name = "processor_aggregator",
+ .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
+ .ids = pad_device_ids,
+ .ops = {
+ .add = xen_acpi_pad_add,
+ .remove = xen_acpi_pad_remove,
+ },
+};
+
+static int __init xen_acpi_pad_stub_init(void)
+{
+ int ret = -ENOSYS;
+ unsigned version;
+
+ if (!xen_initial_domain())
+ return -ENODEV;
+
+ version = HYPERVISOR_xen_version(XENVER_version, NULL);
+
+ if ((version >> 16 >= 4) && ((version & 0xffff) >= 2)) {
+ ret = acpi_bus_register_driver(&xen_acpi_pad_driver);
+ if (!ret)
+ xen_acpi_pad_registered = true;
+ }
+ return ret;
+}
+#if 0
+/* For testing purposes. */
+static void __exit xen_acpi_pad_stub_exit(void)
+{
+ if (xen_acpi_pad_registered)
+ acpi_bus_unregister_driver(&xen_acpi_pad_driver);
+ /* The driver should have unregistered first ! */
+ if (WARN_ON(xen_acpi_pad_ops))
+ xen_acpi_pad_ops = NULL;
+}
+#endif
+subsys_initcall(xen_acpi_pad_stub_init);
diff --git a/drivers/xen/xen-acpi.h b/drivers/xen/xen-acpi.h
new file mode 100644
index 0000000..a0867b2
--- /dev/null
+++ b/drivers/xen/xen-acpi.h
@@ -0,0 +1,2 @@
+int xen_register_acpi_pad_owner(struct acpi_device_ops *ops);
+int xen_unregister_acpi_pad_owner(struct acpi_device_ops *ops);
--
1.7.7.6
>
> IMHO to prevent mwait #UD, native pad should never have chance to register
> successfully when running under Xen. So it's better never unregister/disable
> xen pad.
With the registration stub I mentioned that won't be a problem.
>
> Konrad Rzeszutek Wilk wrote:
> >> --- a/drivers/xen/Makefile
> >> +++ b/drivers/xen/Makefile
> >> @@ -29,6 +29,7 @@ obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o
> >> obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/
> >> obj-$(CONFIG_XEN_PRIVCMD) += xen-privcmd.o
> >> obj-$(CONFIG_XEN_ACPI_PROCESSOR) += xen-acpi-processor.o
> >> +obj-$(CONFIG_XEN_DOM0) += xen_acpi_pad.o
> >
> > We should have a Kconfig option. In it, please mention what
> > version of hypervisor supports this functionality.
> >
>
> Kconfig option for xen pad is not preferred, considering if we disable xen
> pad and then register native pad driver? (of course the precondition is that
> we do not register stub for xen).
That should be OK with the stub.
>
> >> +#include <linux/kernel.h>
> >> +#include <linux/types.h>
> >> +#include <acpi/acpi_bus.h>
> >> +#include <acpi/acpi_drivers.h>
> >> +#include <asm/xen/hypercall.h>
> >> +
> >> +#if defined(CONFIG_ACPI_PROCESSOR_AGGREGATOR) || \
> >> + defined(CONFIG_ACPI_PROCESSOR_AGGREGATOR_MODULE)
> >
> > I don't think you need that.
> >
>
> OK.
>
> >> +
> >> +static int __init xen_acpi_pad_init(void)
> >> +{
> >> + /* Only DOM0 is responsible for Xen acpi pad */
> >> + if (xen_initial_domain())
> >> + return acpi_bus_register_driver(&xen_acpi_pad_driver); +
> >> + return -ENODEV;
> >> +}
> >> +subsys_initcall(xen_acpi_pad_init);
> >
> >
> > No way of making this a module? It would be nice - perhaps have a stub
> > function that registers the bus but does not do anything until this
> > proper module is loaded?
> >
>
> It's doable but not preferred, reason as above.
>
> >> +
> >> +#endif
> >> diff --git a/include/xen/interface/platform.h
> >> b/include/xen/interface/platform.h index 4755b5f..0f44376 100644 ---
> >> a/include/xen/interface/platform.h +++
> >> b/include/xen/interface/platform.h @@ -324,6 +324,22 @@ struct
> >> xenpf_cpu_ol { };
> >> DEFINE_GUEST_HANDLE_STRUCT(xenpf_cpu_ol);
> >>
> >> +/*
> >> + * CMD 58 and 59 are reserved for cpu hotadd and memory hotadd,
> >> + * which already occupied at Xen hypervisor side.
> > ^- are
> >
>
> Sure.
>
> Thanks,
> Jinsong
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