[PATCH V2 00/10] Drivers: hv: vmbus: Enable kexec and other misc cleanup

[PATCH V2 00/10] Drivers: hv: vmbus: Enable kexec and other misc cleanup

[K. Y. Srinivasan]

In addition to enabling kexec, this patch-set has a bunch of miscellaneous
fixes.

In this version of the patch-set; I have fixed up the subject line for couple
of patches (Greg)

Alex Ng (1):
  Drivers: hv: balloon: Enable dynamic memory protocol negotiation with
    Windows 10 hosts

K. Y. Srinivasan (1):
  Drivers: hv: vmbus: Permit sending of packets without payload

Vitaly Kuznetsov (8):
  cpu-hotplug: export cpu_hotplug_enable/cpu_hotplug_disable
  Drivers: hv: vmbus: use cpu_hotplug_enable/disable
  Drivers: hv: vmbus: remove hv_synic_free_cpu() call from
    hv_synic_cleanup()
  Drivers: hv: vmbus: add special kexec handler
  Drivers: hv: don't do hypercalls when hypercall_page is NULL
  Drivers: hv: vmbus: use 'die' notification chain instead of 'panic'
  Drivers: hv: kvp: check kzalloc return value
  Drivers: hv: fcopy: dynamically allocate smsg_out in
    fcopy_send_data()

 Documentation/power/suspend-and-cpuhotplug.txt |    6 +-
 arch/x86/include/asm/mshyperv.h                |    2 +
 arch/x86/kernel/cpu/mshyperv.c                 |   30 +++++++++
 drivers/hv/channel.c                           |    4 +-
 drivers/hv/hv.c                                |   15 +++--
 drivers/hv/hv_balloon.c                        |   26 ++++++--
 drivers/hv/hv_fcopy.c                          |   21 ++++---
 drivers/hv/hv_kvp.c                            |    3 +
 drivers/hv/vmbus_drv.c                         |   76 +++++++++---------------
 kernel/cpu.c                                   |   13 +++--
 10 files changed, 119 insertions(+), 77 deletions(-)

-- 
1.7.4.1

[PATCH V2 01/10] cpu-hotplug: export cpu_hotplug_enable/cpu_hotplug_disable

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

Loaded Hyper-V module will use these functions to disable CPU
hotplug under certain circumstances. Convert cpu_hotplug_disabled
to a counter (protected by cpu_add_remove_lock) to support e.g.
disable -> disable -> enable call sequences.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 Documentation/power/suspend-and-cpuhotplug.txt |    6 +++---
 kernel/cpu.c                                   |   13 ++++++++-----
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/Documentation/power/suspend-and-cpuhotplug.txt b/Documentation/power/suspend-and-cpuhotplug.txt
index 2850df3..2fc9095 100644
--- a/Documentation/power/suspend-and-cpuhotplug.txt
+++ b/Documentation/power/suspend-and-cpuhotplug.txt
@@ -72,7 +72,7 @@ More details follow:
                                         |
                                         v
                            Disable regular cpu hotplug
-                        by setting cpu_hotplug_disabled=1
+                        by increasing cpu_hotplug_disabled
                                         |
                                         v
                             Release cpu_add_remove_lock
@@ -89,7 +89,7 @@ Resuming back is likewise, with the counterparts being (in the order of
 execution during resume):
 * enable_nonboot_cpus() which involves:
    |  Acquire cpu_add_remove_lock
-   |  Reset cpu_hotplug_disabled to 0, thereby enabling regular cpu hotplug
+   |  Decrease cpu_hotplug_disabled, thereby enabling regular cpu hotplug
    |  Call _cpu_up() [for all those cpus in the frozen_cpus mask, in a loop]
    |  Release cpu_add_remove_lock
    v
@@ -120,7 +120,7 @@ after the entire cycle is complete (i.e., suspend + resume).
                            Acquire cpu_add_remove_lock
                                         |
                                         v
-                          If cpu_hotplug_disabled is 1
+                          If cpu_hotplug_disabled > 0
                                 return gracefully
                                         |
                                         |
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 94bbe46..8f35ee6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -190,17 +190,19 @@ void cpu_hotplug_done(void)
 void cpu_hotplug_disable(void)
 {
 	cpu_maps_update_begin();
-	cpu_hotplug_disabled = 1;
+	cpu_hotplug_disabled++;
 	cpu_maps_update_done();
 }
+EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
 
 void cpu_hotplug_enable(void)
 {
 	cpu_maps_update_begin();
-	cpu_hotplug_disabled = 0;
+	if (cpu_hotplug_disabled)
+		cpu_hotplug_disabled--;
 	cpu_maps_update_done();
 }
-
+EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 #endif	/* CONFIG_HOTPLUG_CPU */
 
 /* Need to know about CPUs going up/down? */
@@ -600,7 +602,7 @@ int disable_nonboot_cpus(void)
 	if (!error) {
 		BUG_ON(num_online_cpus() > 1);
 		/* Make sure the CPUs won't be enabled by someone else */
-		cpu_hotplug_disabled = 1;
+		cpu_hotplug_disabled++;
 	} else {
 		pr_err("Non-boot CPUs are not disabled\n");
 	}
@@ -622,7 +624,8 @@ void __ref enable_nonboot_cpus(void)
 
 	/* Allow everyone to use the CPU hotplug again */
 	cpu_maps_update_begin();
-	cpu_hotplug_disabled = 0;
+	if (cpu_hotplug_disabled)
+		cpu_hotplug_disabled--;
 	if (cpumask_empty(frozen_cpus))
 		goto out;
 
-- 
1.7.4.1

[PATCH V2 02/10] Drivers: hv: vmbus: use cpu_hotplug_enable/disable

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

Commit e513229b4c38 ("Drivers: hv: vmbus: prevent cpu offlining on newer
hypervisors") was altering smp_ops.cpu_disable to prevent CPU offlining.
We can bo better by using cpu_hotplug_enable/disable functions instead
of such hard-coding.

Reported-by: Radim Kr.má <rkrcmar@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/vmbus_drv.c |   38 ++++----------------------------------
 1 files changed, 4 insertions(+), 34 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index cf20400..6de65fb 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -763,38 +763,6 @@ static void vmbus_isr(void)
 	}
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static int hyperv_cpu_disable(void)
-{
-	return -ENOSYS;
-}
-
-static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
-{
-	static void *previous_cpu_disable;
-
-	/*
-	 * Offlining a CPU when running on newer hypervisors (WS2012R2, Win8,
-	 * ...) is not supported at this moment as channel interrupts are
-	 * distributed across all of them.
-	 */
-
-	if ((vmbus_proto_version == VERSION_WS2008) ||
-	    (vmbus_proto_version == VERSION_WIN7))
-		return;
-
-	if (vmbus_loaded) {
-		previous_cpu_disable = smp_ops.cpu_disable;
-		smp_ops.cpu_disable = hyperv_cpu_disable;
-		pr_notice("CPU offlining is not supported by hypervisor\n");
-	} else if (previous_cpu_disable)
-		smp_ops.cpu_disable = previous_cpu_disable;
-}
-#else
-static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
-{
-}
-#endif
 
 /*
  * vmbus_bus_init -Main vmbus driver initialization routine.
@@ -836,7 +804,8 @@ static int vmbus_bus_init(int irq)
 	if (ret)
 		goto err_alloc;
 
-	hv_cpu_hotplug_quirk(true);
+	if (vmbus_proto_version > VERSION_WIN7)
+		cpu_hotplug_disable();
 
 	/*
 	 * Only register if the crash MSRs are available
@@ -1121,7 +1090,8 @@ static void __exit vmbus_exit(void)
 		smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
 	}
 	acpi_bus_unregister_driver(&vmbus_acpi_driver);
-	hv_cpu_hotplug_quirk(false);
+	if (vmbus_proto_version > VERSION_WIN7)
+		cpu_hotplug_enable();
 }
 
 
-- 
1.7.4.1

[PATCH V2 03/10] Drivers: hv: vmbus: remove hv_synic_free_cpu() call from hv_synic_cleanup()

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

We already have hv_synic_free() which frees all per-cpu pages for all
CPUs, let's remove the hv_synic_free_cpu() call from hv_synic_cleanup()
so it will be possible to do separate cleanup (writing to MSRs) and final
freeing. This is going to be used to assist kexec.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv.c        |    2 --
 drivers/hv/vmbus_drv.c |    1 +
 2 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index d3943bc..5b87042 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -530,6 +530,4 @@ void hv_synic_cleanup(void *arg)
 	rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 	sctrl.enable = 0;
 	wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
-
-	hv_synic_free_cpu(cpu);
 }
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 6de65fb..58a9344 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1089,6 +1089,7 @@ static void __exit vmbus_exit(void)
 		tasklet_kill(hv_context.event_dpc[cpu]);
 		smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
 	}
+	hv_synic_free();
 	acpi_bus_unregister_driver(&vmbus_acpi_driver);
 	if (vmbus_proto_version > VERSION_WIN7)
 		cpu_hotplug_enable();
-- 
1.7.4.1

[PATCH V2 04/10] Drivers: hv: vmbus: add special kexec handler

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

When general-purpose kexec (not kdump) is being performed in Hyper-V guest
the newly booted kernel fails with an MCE error coming from the host. It
is the same error which was fixed in the "Drivers: hv: vmbus: Implement
the protocol for tearing down vmbus state" commit - monitor pages remain
special and when they're being written to (as the new kernel doesn't know
these pages are special) bad things happen. We need to perform some
minimalistic cleanup before booting a new kernel on kexec. To do so we
need to register a special machine_ops.shutdown handler to be executed
before the native_machine_shutdown(). Registering a shutdown notification
handler via the register_reboot_notifier() call is not sufficient as it
happens to early for our purposes. machine_ops is not being exported to
modules (and I don't think we want to export it) so let's do this in
mshyperv.c

The minimalistic cleanup consists of cleaning up clockevents, synic MSRs,
guest os id MSR, and hypercall MSR.

Kdump doesn't require all this stuff as it lives in a separate memory
space.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 arch/x86/include/asm/mshyperv.h |    2 ++
 arch/x86/kernel/cpu/mshyperv.c  |   30 ++++++++++++++++++++++++++++++
 drivers/hv/vmbus_drv.c          |   14 ++++++++++++++
 3 files changed, 46 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index c163215..d3db910 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -20,4 +20,6 @@ void hyperv_vector_handler(struct pt_regs *regs);
 void hv_setup_vmbus_irq(void (*handler)(void));
 void hv_remove_vmbus_irq(void);
 
+void hv_setup_kexec_handler(void (*handler)(void));
+void hv_remove_kexec_handler(void);
 #endif
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 939155f..efc20a0 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -18,6 +18,9 @@
 #include <linux/efi.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#ifdef CONFIG_KEXEC
+#include <linux/kexec.h>
+#endif
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv.h>
@@ -28,12 +31,14 @@
 #include <asm/i8259.h>
 #include <asm/apic.h>
 #include <asm/timer.h>
+#include <asm/reboot.h>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);
 
 #if IS_ENABLED(CONFIG_HYPERV)
 static void (*vmbus_handler)(void);
+static void (*hv_kexec_handler)(void);
 
 void hyperv_vector_handler(struct pt_regs *regs)
 {
@@ -69,6 +74,28 @@ void hv_remove_vmbus_irq(void)
 }
 EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
 EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
+
+void hv_setup_kexec_handler(void (*handler)(void))
+{
+	hv_kexec_handler = handler;
+}
+EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
+
+void hv_remove_kexec_handler(void)
+{
+	/* We have no way to deallocate the interrupt gate */
+	hv_kexec_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
+
+static void hv_machine_shutdown(void)
+{
+#ifdef CONFIG_KEXEC
+	if (kexec_in_progress && hv_kexec_handler)
+		hv_kexec_handler();
+#endif
+	native_machine_shutdown();
+}
 #endif
 
 static uint32_t  __init ms_hyperv_platform(void)
@@ -143,6 +170,9 @@ static void __init ms_hyperv_init_platform(void)
 	no_timer_check = 1;
 #endif
 
+#if IS_ENABLED(CONFIG_HYPERV)
+	machine_ops.shutdown = hv_machine_shutdown;
+#endif
 }
 
 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 58a9344..7de3e10 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1029,6 +1029,17 @@ static struct acpi_driver vmbus_acpi_driver = {
 	},
 };
 
+static void hv_kexec_handler(void)
+{
+	int cpu;
+
+	hv_synic_clockevents_cleanup();
+	vmbus_initiate_unload();
+	for_each_online_cpu(cpu)
+		smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
+	hv_cleanup();
+};
+
 static int __init hv_acpi_init(void)
 {
 	int ret, t;
@@ -1061,6 +1072,8 @@ static int __init hv_acpi_init(void)
 	if (ret)
 		goto cleanup;
 
+	hv_setup_kexec_handler(hv_kexec_handler);
+
 	return 0;
 
 cleanup:
@@ -1073,6 +1086,7 @@ static void __exit vmbus_exit(void)
 {
 	int cpu;
 
+	hv_remove_kexec_handler();
 	vmbus_connection.conn_state = DISCONNECTED;
 	hv_synic_clockevents_cleanup();
 	vmbus_disconnect();
-- 
1.7.4.1

Re: [PATCH V2 04/10] Drivers: hv: vmbus: add special kexec handler

[Olaf Hering]

On Thu, Jun 04, K. Y. Srinivasan wrote:

> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -18,6 +18,9 @@
>  #include <linux/efi.h>
>  #include <linux/interrupt.h>
>  #include <linux/irq.h>
> +#ifdef CONFIG_KEXEC
> +#include <linux/kexec.h>
> +#endif

Is this #ifdef required?

Olaf

Re: [PATCH V2 04/10] Drivers: hv: vmbus: add special kexec handler

[Vitaly Kuznetsov]

Olaf Hering <olaf@aepfle.de> writes:

> On Thu, Jun 04, K. Y. Srinivasan wrote:
>
>> +++ b/arch/x86/kernel/cpu/mshyperv.c
>> @@ -18,6 +18,9 @@
>>  #include <linux/efi.h>
>>  #include <linux/interrupt.h>
>>  #include <linux/irq.h>
>> +#ifdef CONFIG_KEXEC
>> +#include <linux/kexec.h>
>> +#endif
>
> Is this #ifdef required?
>

No, it's not, but other parts of the same patch do (e.g. there is no
kexec_in_progress without CONFIG_KEXEC). We can probably omit #ifdef
here but I'm not sure it makes sense.

-- 
  Vitaly

Re: [PATCH V2 04/10] Drivers: hv: vmbus: add special kexec handler

[Greg KH]

On Tue, Jun 23, 2015 at 06:28:36PM +0200, Vitaly Kuznetsov wrote:
> Olaf Hering <olaf@aepfle.de> writes:
> 
> > On Thu, Jun 04, K. Y. Srinivasan wrote:
> >
> >> +++ b/arch/x86/kernel/cpu/mshyperv.c
> >> @@ -18,6 +18,9 @@
> >>  #include <linux/efi.h>
> >>  #include <linux/interrupt.h>
> >>  #include <linux/irq.h>
> >> +#ifdef CONFIG_KEXEC
> >> +#include <linux/kexec.h>
> >> +#endif
> >
> > Is this #ifdef required?
> >
> 
> No, it's not, but other parts of the same patch do (e.g. there is no
> kexec_in_progress without CONFIG_KEXEC). We can probably omit #ifdef
> here but I'm not sure it makes sense.

No #ifdef should be in a .c file if at all possible, so please remove
them all if you can.  If not, then work to fix up the .h file properly
so that you can.

thanks,

greg k-h

[PATCH V2 05/10] Drivers: hv: don't do hypercalls when hypercall_page is NULL

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

At the very late stage of kexec a driver (which are not being unloaded) can
try to post a message or signal an event. This will crash the kernel as we
already did hv_cleanup() and the hypercall page is NULL.

Move all common (between 32 and 64 bit code) declarations to the beginning
of the do_hypercall() function. Unfortunately we have to write the
!hypercall_page check twice to not mix declarations and code.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 5b87042..41d8072 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -93,11 +93,14 @@ static int query_hypervisor_info(void)
  */
 static u64 do_hypercall(u64 control, void *input, void *output)
 {
-#ifdef CONFIG_X86_64
-	u64 hv_status = 0;
 	u64 input_address = (input) ? virt_to_phys(input) : 0;
 	u64 output_address = (output) ? virt_to_phys(output) : 0;
 	void *hypercall_page = hv_context.hypercall_page;
+#ifdef CONFIG_X86_64
+	u64 hv_status = 0;
+
+	if (!hypercall_page)
+		return (u64)ULLONG_MAX;
 
 	__asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
 	__asm__ __volatile__("call *%3" : "=a" (hv_status) :
@@ -112,13 +115,13 @@ static u64 do_hypercall(u64 control, void *input, void *output)
 	u32 control_lo = control & 0xFFFFFFFF;
 	u32 hv_status_hi = 1;
 	u32 hv_status_lo = 1;
-	u64 input_address = (input) ? virt_to_phys(input) : 0;
 	u32 input_address_hi = input_address >> 32;
 	u32 input_address_lo = input_address & 0xFFFFFFFF;
-	u64 output_address = (output) ? virt_to_phys(output) : 0;
 	u32 output_address_hi = output_address >> 32;
 	u32 output_address_lo = output_address & 0xFFFFFFFF;
-	void *hypercall_page = hv_context.hypercall_page;
+
+	if (!hypercall_page)
+		return (u64)ULLONG_MAX;
 
 	__asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
 			      "=a"(hv_status_lo) : "d" (control_hi),
-- 
1.7.4.1

[PATCH V2 06/10] Drivers: hv: vmbus: use 'die' notification chain instead of 'panic'

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

current_pt_regs() returns regs of the userspace process and in case of
kernel crash this is not what we need to report. E.g. when we trigger
crash with sysrq we see the following:
...
 RIP: 0010:[<ffffffff815b8696>]  [<ffffffff815b8696>] sysrq_handle_crash+0x16/0x20
 RSP: 0018:ffff8800db0a7d88  EFLAGS: 00010246
 RAX: 000000000000000f RBX: ffffffff820a0660 RCX: 0000000000000000
...
at the same time current_pt_regs() give us:
ip=7f899ea7e9e0, ax=ffffffffffffffda, bx=26c81a0, cx=7f899ea7e9e0, ...
These registers come from the userspace process triggered the crash. As we
don't even know which process it was this information is rather useless.

When kernel crash happens proper regs are being passed to all receivers on
the die_chain (and panic_notifier_list is being notified with the string
passed to panic() only). Let's move our Hyper-V MSR reporter there. This
change has the following implication: when panic() is called manually from
some other part of kernel we won't be reporting crash to the hypervisor
(but we have no valuable information to report anyway).

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/vmbus_drv.c |   23 ++++++++++-------------
 1 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 7de3e10..d2e20f0 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -39,6 +39,7 @@
 #include <asm/mshyperv.h>
 #include <linux/notifier.h>
 #include <linux/ptrace.h>
+#include <linux/kdebug.h>
 #include "hyperv_vmbus.h"
 
 static struct acpi_device  *hv_acpi_dev;
@@ -48,12 +49,11 @@ static struct completion probe_event;
 static int irq;
 
 
-static int hyperv_panic_event(struct notifier_block *nb,
-			unsigned long event, void *ptr)
+static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
+			    void *args)
 {
-	struct pt_regs *regs;
-
-	regs = current_pt_regs();
+	struct die_args *die = (struct die_args *)args;
+	struct pt_regs *regs = die->regs;
 
 	wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip);
 	wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax);
@@ -68,8 +68,8 @@ static int hyperv_panic_event(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
-static struct notifier_block hyperv_panic_block = {
-	.notifier_call = hyperv_panic_event,
+static struct notifier_block hyperv_die_block = {
+	.notifier_call = hyperv_die_event,
 };
 
 struct resource hyperv_mmio = {
@@ -811,8 +811,7 @@ static int vmbus_bus_init(int irq)
 	 * Only register if the crash MSRs are available
 	 */
 	if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
-		atomic_notifier_chain_register(&panic_notifier_list,
-					       &hyperv_panic_block);
+		register_die_notifier(&hyperv_die_block);
 	}
 
 	vmbus_request_offers();
@@ -1093,10 +1092,8 @@ static void __exit vmbus_exit(void)
 	hv_remove_vmbus_irq();
 	tasklet_kill(&msg_dpc);
 	vmbus_free_channels();
-	if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
-		atomic_notifier_chain_unregister(&panic_notifier_list,
-						 &hyperv_panic_block);
-	}
+	if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
+		unregister_die_notifier(&hyperv_die_block);
 	bus_unregister(&hv_bus);
 	hv_cleanup();
 	for_each_online_cpu(cpu) {
-- 
1.7.4.1

Re: [PATCH V2 06/10] Drivers: hv: vmbus: use 'die' notification chain instead of 'panic'

[Vitaly Kuznetsov]

"K. Y. Srinivasan" <kys@microsoft.com> writes:

> From: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> current_pt_regs() returns regs of the userspace process and in case of
> kernel crash this is not what we need to report. E.g. when we trigger
> crash with sysrq we see the following:
> ...
>  RIP: 0010:[<ffffffff815b8696>]  [<ffffffff815b8696>] sysrq_handle_crash+0x16/0x20
>  RSP: 0018:ffff8800db0a7d88  EFLAGS: 00010246
>  RAX: 000000000000000f RBX: ffffffff820a0660 RCX: 0000000000000000
> ...
> at the same time current_pt_regs() give us:
> ip=7f899ea7e9e0, ax=ffffffffffffffda, bx=26c81a0, cx=7f899ea7e9e0, ...
> These registers come from the userspace process triggered the crash. As we
> don't even know which process it was this information is rather useless.
>
> When kernel crash happens proper regs are being passed to all receivers on
> the die_chain (and panic_notifier_list is being notified with the string
> passed to panic() only). Let's move our Hyper-V MSR reporter there. This
> change has the following implication: when panic() is called manually from
> some other part of kernel we won't be reporting crash to the hypervisor
> (but we have no valuable information to report anyway).

We can, actually, do better: we can has this reporter in _both_
notification chains (with a static preventng double reporting). In this
case we'll have panics reported on e.g BUG_ON()

As this patch is still not merged I'll fix and resend instead of
creating a separate patch.

-- 
  Vitaly

[PATCH V2 07/10] Drivers: hv: kvp: check kzalloc return value

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

kzalloc() return value check was accidentally lost in 11bc3a5fa91f:
"Drivers: hv: kvp: convert to hv_utils_transport" commit.

We don't need to reset kvp_transaction.state here as we have the
kvp_timeout_func() timeout function and in case we're in OOM situation
it is preferable to wait.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_kvp.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index d85798d..74c38a9 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -353,6 +353,9 @@ kvp_send_key(struct work_struct *dummy)
 		return;
 
 	message = kzalloc(sizeof(*message), GFP_KERNEL);
+	if (!message)
+		return;
+
 	message->kvp_hdr.operation = operation;
 	message->kvp_hdr.pool = pool;
 	in_msg = kvp_transaction.kvp_msg;
-- 
1.7.4.1

[PATCH V2 08/10] Drivers: hv: fcopy: dynamically allocate smsg_out in fcopy_send_data()

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

struct hv_start_fcopy is too big to be on stack on i386, the following
warning is reported:

>> drivers/hv/hv_fcopy.c:159:1: warning: the frame size of 1088 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_fcopy.c |   21 +++++++++++++--------
 1 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index b50dd33..db4b887 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -116,7 +116,7 @@ static int fcopy_handle_handshake(u32 version)
 
 static void fcopy_send_data(struct work_struct *dummy)
 {
-	struct hv_start_fcopy smsg_out;
+	struct hv_start_fcopy *smsg_out = NULL;
 	int operation = fcopy_transaction.fcopy_msg->operation;
 	struct hv_start_fcopy *smsg_in;
 	void *out_src;
@@ -136,21 +136,24 @@ static void fcopy_send_data(struct work_struct *dummy)
 	switch (operation) {
 	case START_FILE_COPY:
 		out_len = sizeof(struct hv_start_fcopy);
-		memset(&smsg_out, 0, out_len);
-		smsg_out.hdr.operation = operation;
+		smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
+		if (!smsg_out)
+			return;
+
+		smsg_out->hdr.operation = operation;
 		smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
 
 		utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 				UTF16_LITTLE_ENDIAN,
-				(__u8 *)&smsg_out.file_name, W_MAX_PATH - 1);
+				(__u8 *)&smsg_out->file_name, W_MAX_PATH - 1);
 
 		utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 				UTF16_LITTLE_ENDIAN,
-				(__u8 *)&smsg_out.path_name, W_MAX_PATH - 1);
+				(__u8 *)&smsg_out->path_name, W_MAX_PATH - 1);
 
-		smsg_out.copy_flags = smsg_in->copy_flags;
-		smsg_out.file_size = smsg_in->file_size;
-		out_src = &smsg_out;
+		smsg_out->copy_flags = smsg_in->copy_flags;
+		smsg_out->file_size = smsg_in->file_size;
+		out_src = smsg_out;
 		break;
 
 	default:
@@ -168,6 +171,8 @@ static void fcopy_send_data(struct work_struct *dummy)
 			fcopy_transaction.state = HVUTIL_READY;
 		}
 	}
+	kfree(smsg_out);
+
 	return;
 }
 
-- 
1.7.4.1

[PATCH V2 09/10] Drivers: hv: balloon: Enable dynamic memory protocol negotiation with Windows 10 hosts

[K. Y. Srinivasan]

From: Alex Ng <alexng@microsoft.com>

Support Win10 protocol for Dynamic Memory. Thia patch allows guests on Win10 hosts
to hot-add memory even when dynamic memory is not enabled on the guest.

Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_balloon.c |   26 ++++++++++++++++++++------
 1 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 8a725cd..b853b4b 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -62,11 +62,13 @@
 enum {
 	DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
 	DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
+	DYNMEM_PROTOCOL_VERSION_3 = DYNMEM_MAKE_VERSION(2, 0),
 
 	DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
 	DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
+	DYNMEM_PROTOCOL_VERSION_WIN10 = DYNMEM_PROTOCOL_VERSION_3,
 
-	DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN8
+	DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN10
 };
 
 
@@ -1296,13 +1298,25 @@ static void version_resp(struct hv_dynmem_device *dm,
 	if (dm->next_version == 0)
 		goto version_error;
 
-	dm->next_version = 0;
 	memset(&version_req, 0, sizeof(struct dm_version_request));
 	version_req.hdr.type = DM_VERSION_REQUEST;
 	version_req.hdr.size = sizeof(struct dm_version_request);
 	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
-	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN7;
-	version_req.is_last_attempt = 1;
+	version_req.version.version = dm->next_version;
+
+	/*
+	 * Set the next version to try in case current version fails.
+	 * Win7 protocol ought to be the last one to try.
+	 */
+	switch (version_req.version.version) {
+	case DYNMEM_PROTOCOL_VERSION_WIN8:
+		dm->next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
+		version_req.is_last_attempt = 0;
+		break;
+	default:
+		dm->next_version = 0;
+		version_req.is_last_attempt = 1;
+	}
 
 	ret = vmbus_sendpacket(dm->dev->channel, &version_req,
 				sizeof(struct dm_version_request),
@@ -1442,7 +1456,7 @@ static int balloon_probe(struct hv_device *dev,
 
 	dm_device.dev = dev;
 	dm_device.state = DM_INITIALIZING;
-	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
+	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN8;
 	init_completion(&dm_device.host_event);
 	init_completion(&dm_device.config_event);
 	INIT_LIST_HEAD(&dm_device.ha_region_list);
@@ -1474,7 +1488,7 @@ static int balloon_probe(struct hv_device *dev,
 	version_req.hdr.type = DM_VERSION_REQUEST;
 	version_req.hdr.size = sizeof(struct dm_version_request);
 	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
-	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN8;
+	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN10;
 	version_req.is_last_attempt = 0;
 
 	ret = vmbus_sendpacket(dev->channel, &version_req,
-- 
1.7.4.1

[PATCH V2 10/10] Drivers: hv: vmbus: Permit sending of packets without payload

[K. Y. Srinivasan]

The guest may have to send a completion packet back to the host.
To support this usage, permit sending a packet without a payload -
we would be only sending the descriptor in this case.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/channel.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 603ce97..c4dcab0 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -601,6 +601,7 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
 	u64 aligned_data = 0;
 	int ret;
 	bool signal = false;
+	int num_vecs = ((bufferlen != 0) ? 3 : 1);
 
 
 	/* Setup the descriptor */
@@ -618,7 +619,8 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
 	bufferlist[2].iov_base = &aligned_data;
 	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
-	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, num_vecs,
+				  &signal);
 
 	/*
 	 * Signalling the host is conditional on many factors:
-- 
1.7.4.1

Re: [PATCH V2 01/10] cpu-hotplug: export cpu_hotplug_enable/cpu_hotplug_disable

[Greg KH]

On Thu, Jun 04, 2015 at 04:26:07PM -0700, K. Y. Srinivasan wrote:
> From: Vitaly Kuznetsov <vkuznets@redhat.com>
> 
> Loaded Hyper-V module will use these functions to disable CPU
> hotplug under certain circumstances. Convert cpu_hotplug_disabled
> to a counter (protected by cpu_add_remove_lock) to support e.g.
> disable -> disable -> enable call sequences.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> ---
>  Documentation/power/suspend-and-cpuhotplug.txt |    6 +++---
>  kernel/cpu.c                                   |   13 ++++++++-----
>  2 files changed, 11 insertions(+), 8 deletions(-)

This changes the logic a bit, so I need an ack from the maintainers of
the CPU hotplug code before I can accept this...

thanks,

greg k-h