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

[PATCH 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.

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):
  Drivers: hv: vmbus: remove hv_synic_free_cpu() call from
    hv_synic_cleanup()
  kexec: define kexec_in_progress in !CONFIG_KEXEC case
  Drivers: hv: vmbus: add special kexec handler
  Drivers: hv: don't do hypercalls when hypercall_page is NULL
  Drivers: hv: vmbus: add special crash handler
  Drivers: hv: vmbus: prefer 'die' notification chain to 'panic'
  Drivers: hv: kvp: check kzalloc return value
  Drivers: hv: fcopy: dynamically allocate smsg_out in
    fcopy_send_data()

 arch/x86/include/asm/mshyperv.h |    4 ++
 arch/x86/kernel/cpu/mshyperv.c  |   46 ++++++++++++++++++++++++++
 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          |   69 ++++++++++++++++++++++++++++++++++++--
 include/linux/kexec.h           |    1 +
 9 files changed, 163 insertions(+), 26 deletions(-)

-- 
1.7.4.1

[PATCH 01/10] 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 cf20400..00d5158 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1120,6 +1120,7 @@ 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);
 	hv_cpu_hotplug_quirk(false);
 }
-- 
1.7.4.1

[PATCH 02/10] kexec: define kexec_in_progress in !CONFIG_KEXEC case

[K. Y. Srinivasan]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

If some piece of code wants to check kexec_in_progress it has to be put
in #ifdef CONFIG_KEXEC block to not break the build in !CONFIG_KEXEC
case. Overcome this limitation by defining kexec_in_progress to false.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 include/linux/kexec.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e804306..b63218f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -323,6 +323,7 @@ struct pt_regs;
 struct task_struct;
 static inline void crash_kexec(struct pt_regs *regs) { }
 static inline int kexec_should_crash(struct task_struct *p) { return 0; }
+#define kexec_in_progress false
 #endif /* CONFIG_KEXEC */
 
 #endif /* !defined(__ASSEBMLY__) */
-- 
1.7.4.1

[PATCH 03/10] 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  |   24 ++++++++++++++++++++++++
 drivers/hv/vmbus_drv.c          |   14 ++++++++++++++
 3 files changed, 40 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..09911aa 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -18,6 +18,7 @@
 #include <linux/efi.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/kexec.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv.h>
@@ -28,10 +29,13 @@
 #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);
 
+static void (*hv_kexec_handler)(void);
+
 #if IS_ENABLED(CONFIG_HYPERV)
 static void (*vmbus_handler)(void);
 
@@ -69,8 +73,27 @@ 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)
+{
+	hv_kexec_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
 #endif
 
+static void hv_machine_shutdown(void)
+{
+	if (kexec_in_progress && hv_kexec_handler)
+		hv_kexec_handler();
+	native_machine_shutdown();
+}
+
 static uint32_t  __init ms_hyperv_platform(void)
 {
 	u32 eax;
@@ -143,6 +166,7 @@ static void __init ms_hyperv_init_platform(void)
 	no_timer_check = 1;
 #endif
 
+	machine_ops.shutdown = hv_machine_shutdown;
 }
 
 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 00d5158..31748a2 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1060,6 +1060,17 @@ 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;
@@ -1092,6 +1103,8 @@ static int __init hv_acpi_init(void)
 	if (ret)
 		goto cleanup;
 
+	hv_setup_kexec_handler(hv_kexec_handler);
+
 	return 0;
 
 cleanup:
@@ -1104,6 +1117,7 @@ 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

[PATCH 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.

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):
  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.
  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.
  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                           |    3 +-
 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, 118 insertions(+), 77 deletions(-)

-- 
1.7.4.1