[PATCH 4.14 10/50] xen: Fix event channel callback via INTX/GSI

[PATCH 4.14 10/50] xen: Fix event channel callback via INTX/GSI

[Greg Kroah-Hartman]

From: David Woodhouse <dwmw@amazon.co.uk>

[ Upstream commit 3499ba8198cad47b731792e5e56b9ec2a78a83a2 ]

For a while, event channel notification via the PCI platform device
has been broken, because we attempt to communicate with xenstore before
we even have notifications working, with the xs_reset_watches() call
in xs_init().

We tend to get away with this on Xen versions below 4.0 because we avoid
calling xs_reset_watches() anyway, because xenstore might not cope with
reading a non-existent key. And newer Xen *does* have the vector
callback support, so we rarely fall back to INTX/GSI delivery.

To fix it, clean up a bit of the mess of xs_init() and xenbus_probe()
startup. Call xs_init() directly from xenbus_init() only in the !XS_HVM
case, deferring it to be called from xenbus_probe() in the XS_HVM case
instead.

Then fix up the invocation of xenbus_probe() to happen either from its
device_initcall if the callback is available early enough, or when the
callback is finally set up. This means that the hack of calling
xenbus_probe() from a workqueue after the first interrupt, or directly
from the PCI platform device setup, is no longer needed.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20210113132606.422794-2-dwmw2@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm/xen/enlighten.c          |  2 +-
 drivers/xen/events/events_base.c  | 10 ----
 drivers/xen/platform-pci.c        |  1 -
 drivers/xen/xenbus/xenbus.h       |  1 +
 drivers/xen/xenbus/xenbus_comms.c |  8 ---
 drivers/xen/xenbus/xenbus_probe.c | 81 +++++++++++++++++++++++++------
 include/xen/xenbus.h              |  2 +-
 7 files changed, 70 insertions(+), 35 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index ba7f4c8f5c3e4..e8e637c4f354d 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -393,7 +393,7 @@ static int __init xen_guest_init(void)
 	}
 	gnttab_init();
 	if (!xen_initial_domain())
-		xenbus_probe(NULL);
+		xenbus_probe();
 
 	/*
 	 * Making sure board specific code will not set up ops for
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index aca8456752797..8c08c7d46d3d0 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1987,16 +1987,6 @@ static struct irq_chip xen_percpu_chip __read_mostly = {
 	.irq_ack		= ack_dynirq,
 };
 
-int xen_set_callback_via(uint64_t via)
-{
-	struct xen_hvm_param a;
-	a.domid = DOMID_SELF;
-	a.index = HVM_PARAM_CALLBACK_IRQ;
-	a.value = via;
-	return HYPERVISOR_hvm_op(HVMOP_set_param, &a);
-}
-EXPORT_SYMBOL_GPL(xen_set_callback_via);
-
 #ifdef CONFIG_XEN_PVHVM
 /* Vector callbacks are better than PCI interrupts to receive event
  * channel notifications because we can receive vector callbacks on any
diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
index 5d7dcad0b0a0d..4cec8146609ad 100644
--- a/drivers/xen/platform-pci.c
+++ b/drivers/xen/platform-pci.c
@@ -162,7 +162,6 @@ static int platform_pci_probe(struct pci_dev *pdev,
 	ret = gnttab_init();
 	if (ret)
 		goto grant_out;
-	xenbus_probe(NULL);
 	return 0;
 grant_out:
 	gnttab_free_auto_xlat_frames();
diff --git a/drivers/xen/xenbus/xenbus.h b/drivers/xen/xenbus/xenbus.h
index 139539b0ab20d..e6a8d02d35254 100644
--- a/drivers/xen/xenbus/xenbus.h
+++ b/drivers/xen/xenbus/xenbus.h
@@ -114,6 +114,7 @@ int xenbus_probe_node(struct xen_bus_type *bus,
 		      const char *type,
 		      const char *nodename);
 int xenbus_probe_devices(struct xen_bus_type *bus);
+void xenbus_probe(void);
 
 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus);
 
diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index eb5151fc8efab..e5fda0256feb3 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -57,16 +57,8 @@ DEFINE_MUTEX(xs_response_mutex);
 static int xenbus_irq;
 static struct task_struct *xenbus_task;
 
-static DECLARE_WORK(probe_work, xenbus_probe);
-
-
 static irqreturn_t wake_waiting(int irq, void *unused)
 {
-	if (unlikely(xenstored_ready == 0)) {
-		xenstored_ready = 1;
-		schedule_work(&probe_work);
-	}
-
 	wake_up(&xb_waitq);
 	return IRQ_HANDLED;
 }
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 217bcc092a968..fe24e8dcb2b8e 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -674,29 +674,76 @@ void unregister_xenstore_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 
-void xenbus_probe(struct work_struct *unused)
+void xenbus_probe(void)
 {
 	xenstored_ready = 1;
 
+	/*
+	 * In the HVM case, xenbus_init() deferred its call to
+	 * xs_init() in case callbacks were not operational yet.
+	 * So do it now.
+	 */
+	if (xen_store_domain_type == XS_HVM)
+		xs_init();
+
 	/* Notify others that xenstore is up */
 	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 }
-EXPORT_SYMBOL_GPL(xenbus_probe);
 
-static int __init xenbus_probe_initcall(void)
+/*
+ * Returns true when XenStore init must be deferred in order to
+ * allow the PCI platform device to be initialised, before we
+ * can actually have event channel interrupts working.
+ */
+static bool xs_hvm_defer_init_for_callback(void)
 {
-	if (!xen_domain())
-		return -ENODEV;
+#ifdef CONFIG_XEN_PVHVM
+	return xen_store_domain_type == XS_HVM &&
+		!xen_have_vector_callback;
+#else
+	return false;
+#endif
+}
 
-	if (xen_initial_domain() || xen_hvm_domain())
-		return 0;
+static int __init xenbus_probe_initcall(void)
+{
+	/*
+	 * Probe XenBus here in the XS_PV case, and also XS_HVM unless we
+	 * need to wait for the platform PCI device to come up.
+	 */
+	if (xen_store_domain_type == XS_PV ||
+	    (xen_store_domain_type == XS_HVM &&
+	     !xs_hvm_defer_init_for_callback()))
+		xenbus_probe();
 
-	xenbus_probe(NULL);
 	return 0;
 }
-
 device_initcall(xenbus_probe_initcall);
 
+int xen_set_callback_via(uint64_t via)
+{
+	struct xen_hvm_param a;
+	int ret;
+
+	a.domid = DOMID_SELF;
+	a.index = HVM_PARAM_CALLBACK_IRQ;
+	a.value = via;
+
+	ret = HYPERVISOR_hvm_op(HVMOP_set_param, &a);
+	if (ret)
+		return ret;
+
+	/*
+	 * If xenbus_probe_initcall() deferred the xenbus_probe()
+	 * due to the callback not functioning yet, we can do it now.
+	 */
+	if (!xenstored_ready && xs_hvm_defer_init_for_callback())
+		xenbus_probe();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xen_set_callback_via);
+
 /* Set up event channel for xenstored which is run as a local process
  * (this is normally used only in dom0)
  */
@@ -810,11 +857,17 @@ static int __init xenbus_init(void)
 		break;
 	}
 
-	/* Initialize the interface to xenstore. */
-	err = xs_init();
-	if (err) {
-		pr_warn("Error initializing xenstore comms: %i\n", err);
-		goto out_error;
+	/*
+	 * HVM domains may not have a functional callback yet. In that
+	 * case let xs_init() be called from xenbus_probe(), which will
+	 * get invoked at an appropriate time.
+	 */
+	if (xen_store_domain_type != XS_HVM) {
+		err = xs_init();
+		if (err) {
+			pr_warn("Error initializing xenstore comms: %i\n", err);
+			goto out_error;
+		}
 	}
 
 	if ((xen_store_domain_type != XS_LOCAL) &&
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index eba01ab5a55e0..fe9a9fa2ebc45 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -187,7 +187,7 @@ void xs_suspend_cancel(void);
 
 struct work_struct;
 
-void xenbus_probe(struct work_struct *);
+void xenbus_probe(void);
 
 #define XENBUS_IS_ERR_READ(str) ({			\
 	if (!IS_ERR(str) && strlen(str) == 0) {		\
-- 
2.27.0

Re: [PATCH 4.14 00/50] 4.14.218-rc1 review

[Guenter Roeck]

On Fri, Jan 29, 2021 at 12:06:25PM +0100, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.14.218 release.
> There are 50 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Sun, 31 Jan 2021 10:59:01 +0000.
> Anything received after that time might be too late.
> 
Build results:
	total: 168 pass: 168 fail: 0
Qemu test results:
	total: 404 pass: 404 fail: 0

Tested-by: Guenter Roeck <linux@roeck-us.net>

Guenter

Re: [PATCH 4.14 00/50] 4.14.218-rc1 review

[Jon Hunter]

On 29/01/2021 18:21, Guenter Roeck wrote:
> On Fri, Jan 29, 2021 at 12:06:25PM +0100, Greg Kroah-Hartman wrote:
>> This is the start of the stable review cycle for the 4.14.218 release.
>> There are 50 patches in this series, all will be posted as a response
>> to this one.  If anyone has any issues with these being applied, please
>> let me know.


Replying here because I don't have the original.

Test results for stable-v4.14:
    8 builds:	8 pass, 0 fail
    16 boots:	16 pass, 0 fail
    30 tests:	30 pass, 0 fail

Linux version:	4.14.218-rc1-g672a9e33037f
Boards tested:	tegra124-jetson-tk1, tegra20-ventana,
                tegra210-p2371-2180, tegra30-cardhu-a04

Tested-by: Jon Hunter <jonathanh@nvidia.com>

Jon

-- 
nvpublic

Re: [PATCH 4.14 00/50] 4.14.218-rc1 review

[Naresh Kamboju]

On Fri, 29 Jan 2021 at 16:43, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> This is the start of the stable review cycle for the 4.14.218 release.
> There are 50 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 31 Jan 2021 10:59:01 +0000.
> Anything received after that time might be too late.
>
> The whole patch series can be found in one patch at:
>         https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.14.218-rc1.gz
> or in the git tree and branch at:
>         git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.14.y
> and the diffstat can be found below.
>
> thanks,
>
> greg k-h

Results from Linaro’s test farm.
No regressions on arm64, arm, x86_64, and i386.

Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>

Summary
------------------------------------------------------------------------

kernel: 4.14.218-rc1
git repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
git branch: linux-4.14.y
git commit: 672a9e33037fec508dabec093d006a08ef8b749e
git describe: v4.14.217-51-g672a9e33037f
Test details: https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-4.14.y/build/v4.14.217-51-g672a9e33037f

No regressions (compared to build v4.14.217-38-g57121d407faa)

No fixes (compared to build v4.14.217-38-g57121d407faa)

Ran 39115 total tests in the following environments and test suites.

Environments
--------------
- arm
- arm64
- dragonboard-410c - arm64
- hi6220-hikey - arm64
- i386
- juno-r2 - arm64
- juno-r2-compat
- juno-r2-kasan
- mips
- qemu-arm64-kasan
- qemu-x86_64-kasan
- qemu_arm
- qemu_arm64
- qemu_arm64-compat
- qemu_i386
- qemu_x86_64
- qemu_x86_64-compat
- sparc
- x15 - arm
- x86_64
- x86-kasan

Test Suites
-----------
* build
* linux-log-parser
* igt-gpu-tools
* install-android-platform-tools-r2600
* kvm-unit-tests
* ltp-dio-tests
* ltp-fcntl-locktests-tests
* ltp-filecaps-tests
* ltp-fs_bind-tests
* ltp-fs_perms_simple-tests
* ltp-fsx-tests
* ltp-hugetlb-tests
* ltp-io-tests
* ltp-mm-tests
* ltp-sched-tests
* ltp-syscalls-tests
* ltp-tracing-tests
* perf
* fwts
* libhugetlbfs
* ltp-cap_bounds-tests
* ltp-commands-tests
* ltp-controllers-tests
* ltp-cpuhotplug-tests
* ltp-crypto-tests
* ltp-cve-tests
* ltp-fs-tests
* ltp-ipc-tests
* ltp-math-tests
* ltp-nptl-tests
* ltp-pty-tests
* ltp-securebits-tests
* network-basic-tests
* v4l2-compliance
* ltp-containers-tests
* ltp-open-posix-tests
* rcutorture

-- 
Linaro LKFT
https://lkft.linaro.org