RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic
> -Original Message-
> From: KY Srinivasan
> Sent: Monday, June 11, 2018 11:39 AM
> To: Sunil Muthuswamy ; Haiyang Zhang
>
> Cc: de...@linuxdriverproject.org; Stephen Hemminger
>
> Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> over Hyper-V during panic
>
>
>
> > -Original Message-
> > From: Sunil Muthuswamy
> > Sent: Monday, June 11, 2018 10:44 AM
> > To: KY Srinivasan ; Haiyang Zhang
> >
> > Cc: de...@linuxdriverproject.org; Stephen Hemminger
> >
> > Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > over Hyper-V during panic
> >
> >
> >
> > > -Original Message-
> > > From: KY Srinivasan
> > > Sent: Sunday, June 10, 2018 2:54 PM
> > > To: Sunil Muthuswamy ; Haiyang Zhang
> > >
> > > Cc: de...@linuxdriverproject.org; Stephen Hemminger
> > >
> > > Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > > over Hyper-V during panic
> > >
> > >
> > >
> > > > -Original Message-
> > > > From: Sunil Muthuswamy
> > > > Sent: Friday, June 8, 2018 11:39 AM
> > > > To: Haiyang Zhang
> > > > Cc: de...@linuxdriverproject.org; Sunil Muthuswamy
> > > > ; KY Srinivasan ;
> > Stephen
> > > > Hemminger
> > > > Subject: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > over
> > > > Hyper-V during panic
> > > >
> > > > In the VM mode on Hyper-V, currently, when the kernel panics, an
> error
> > > > code and few register values are populated in an MSR and the
> Hypervisor
> > > > notified. This information is collected on the host. The amount of
> > > > information currently collected is found to be limited and not very
> > > > actionable. To gather more actionable data, such as stack trace, the
> > > > proposal is to write one page worth of kmsg data on an allocated page
> > > > and the Hypervisor notified of the page address through the MSR.
> > > >
>
> Snip.
>
> > > > /*
> > > > * vmbus_bus_init -Main vmbus driver initialization routine.
> > > > @@ -1065,6 +1136,38 @@ static int vmbus_bus_init(void)
> > > > * Only register if the crash MSRs are available
> > > > */
> > > > if (ms_hyperv.misc_features &
> > > > HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
> > > > + u64 hyperv_crash_ctl;
> > > > + if (!hv_ctl_table_hdr) {
> > > When vmus_bus_init is invoked, would hv_ctl_table_hdr ever be
> > > Non-NULL?
> Ping.
Missed this somehow. It should not be. Will fix this as well in the next
version.
>
> Snip.
>
> Regards,
>
> K. Y
___
devel mailing list
de...@linuxdriverproject.org
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic
> -Original Message-
> From: Sunil Muthuswamy
> Sent: Monday, June 11, 2018 10:44 AM
> To: KY Srinivasan ; Haiyang Zhang
>
> Cc: de...@linuxdriverproject.org; Stephen Hemminger
>
> Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> over Hyper-V during panic
>
>
>
> > -Original Message-
> > From: KY Srinivasan
> > Sent: Sunday, June 10, 2018 2:54 PM
> > To: Sunil Muthuswamy ; Haiyang Zhang
> >
> > Cc: de...@linuxdriverproject.org; Stephen Hemminger
> >
> > Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > over Hyper-V during panic
> >
> >
> >
> > > -Original Message-
> > > From: Sunil Muthuswamy
> > > Sent: Friday, June 8, 2018 11:39 AM
> > > To: Haiyang Zhang
> > > Cc: de...@linuxdriverproject.org; Sunil Muthuswamy
> > > ; KY Srinivasan ;
> Stephen
> > > Hemminger
> > > Subject: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> over
> > > Hyper-V during panic
> > >
> > > In the VM mode on Hyper-V, currently, when the kernel panics, an error
> > > code and few register values are populated in an MSR and the Hypervisor
> > > notified. This information is collected on the host. The amount of
> > > information currently collected is found to be limited and not very
> > > actionable. To gather more actionable data, such as stack trace, the
> > > proposal is to write one page worth of kmsg data on an allocated page
> > > and the Hypervisor notified of the page address through the MSR.
> > >
Snip.
> > > /*
> > > * vmbus_bus_init -Main vmbus driver initialization routine.
> > > @@ -1065,6 +1136,38 @@ static int vmbus_bus_init(void)
> > >* Only register if the crash MSRs are available
> > >*/
> > > if (ms_hyperv.misc_features &
> > > HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
> > > + u64 hyperv_crash_ctl;
> > > + if (!hv_ctl_table_hdr) {
> > When vmus_bus_init is invoked, would hv_ctl_table_hdr ever be
> > Non-NULL?
Ping.
Snip.
Regards,
K. Y
___
devel mailing list
de...@linuxdriverproject.org
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic
> -Original Message-
> From: KY Srinivasan
> Sent: Sunday, June 10, 2018 2:54 PM
> To: Sunil Muthuswamy ; Haiyang Zhang
>
> Cc: de...@linuxdriverproject.org; Stephen Hemminger
>
> Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> over Hyper-V during panic
>
>
>
> > -Original Message-
> > From: Sunil Muthuswamy
> > Sent: Friday, June 8, 2018 11:39 AM
> > To: Haiyang Zhang
> > Cc: de...@linuxdriverproject.org; Sunil Muthuswamy
> > ; KY Srinivasan ; Stephen
> > Hemminger
> > Subject: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump over
> > Hyper-V during panic
> >
> > In the VM mode on Hyper-V, currently, when the kernel panics, an error
> > code and few register values are populated in an MSR and the Hypervisor
> > notified. This information is collected on the host. The amount of
> > information currently collected is found to be limited and not very
> > actionable. To gather more actionable data, such as stack trace, the
> > proposal is to write one page worth of kmsg data on an allocated page
> > and the Hypervisor notified of the page address through the MSR.
> >
> > - Sysctl option to control the behavior, with ON by default.
> >
> > Cc: K. Y. Srinivasan
> > Cc: Stephen Hemminger
> > Signed-off-by: Sunil Muthuswamy
> > ---
> > Changes since v1:
> > - Added a sysctl config option to allow the user to control if panic message
> > should be reported to Hyper-V.
> >
> > Changes since v2:
> > - Addressed comments from Greg KH.
> > - Moved the sysctl config option from 'kernel.hyperv' to 'kernel.' since the
> > likelihood of having many Hyper-V specific sysctl config options seemed
> less
> > and so having a specific dir for Hyper-V seemed unnecessary overhead.
> >
> > Changes since v3:
> > - The feature is only enabled if the capability is supported by the
> hypervisor.
> > This is done by reading the crash control MSR, in addition to the pre-
> existing
> > check for the hypervisor feature using the CPUID.
> >
> > Changes since v4:
> > - Addressed comments from Dexuan Cui: moved the global variable to
> static.
> > ---
> > Documentation/sysctl/kernel.txt| 11
> > arch/x86/hyperv/hv_init.c | 27 +
> > arch/x86/include/asm/hyperv-tlfs.h | 5 +-
> > arch/x86/include/asm/mshyperv.h| 1 +
> > drivers/hv/vmbus_drv.c | 116
> > +
> > 5 files changed, 158 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/sysctl/kernel.txt
> > b/Documentation/sysctl/kernel.txt
> > index eded671d..5958503 100644
> > --- a/Documentation/sysctl/kernel.txt
> > +++ b/Documentation/sysctl/kernel.txt
> > @@ -39,6 +39,7 @@ show up in /proc/sys/kernel:
> > - hung_task_check_count
> > - hung_task_timeout_secs
> > - hung_task_warnings
> > +- hyperv_record_panic_msg
> > - kexec_load_disabled
> > - kptr_restrict
> > - l2cr[ PPC only ]
> > @@ -374,6 +375,16 @@ This file shows up if CONFIG_DETECT_HUNG_TASK
> is
> > enabled.
> >
> >
> >
> ==
> >
> >
> > +hyperv_record_panic_msg:
> > +
> > +Controls whether the panic kmsg data should be reported to Hyper-V.
> > +
> > +0: do not report panic kmsg data.
> > +
> > +1: report the panic kmsg data. This is the default behavior.
> > +
> >
> +=
> > =
> > +
> > kexec_load_disabled:
> >
> > A toggle indicating if the kexec_load syscall has been disabled. This
> > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> > index cfecc22..af57162 100644
> > --- a/arch/x86/hyperv/hv_init.c
> > +++ b/arch/x86/hyperv/hv_init.c
> > @@ -395,6 +395,33 @@ void hyperv_report_panic(struct pt_regs *regs,
> long
> > err)
> > }
> > EXPORT_SYMBOL_GPL(hyperv_report_panic);
> >
> > +/**
> > + * hyperv_report_panic_msg - report panic message to Hyper-V
> > + * @pa: physical address of the panic page containing the message
> > + * @size: size of the message in the page
> > + */
> > +void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
> > +{
> > + /*
> > +* P3 to contain the physical address of the panic page & P4 to
> > +* contain the size of the panic data in that page. Rest of the
> > +* registers
RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic
> -Original Message-
> From: Sunil Muthuswamy
> Sent: Friday, June 8, 2018 11:39 AM
> To: Haiyang Zhang
> Cc: de...@linuxdriverproject.org; Sunil Muthuswamy
> ; KY Srinivasan ; Stephen
> Hemminger
> Subject: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump over
> Hyper-V during panic
>
> In the VM mode on Hyper-V, currently, when the kernel panics, an error
> code and few register values are populated in an MSR and the Hypervisor
> notified. This information is collected on the host. The amount of
> information currently collected is found to be limited and not very
> actionable. To gather more actionable data, such as stack trace, the
> proposal is to write one page worth of kmsg data on an allocated page
> and the Hypervisor notified of the page address through the MSR.
>
> - Sysctl option to control the behavior, with ON by default.
>
> Cc: K. Y. Srinivasan
> Cc: Stephen Hemminger
> Signed-off-by: Sunil Muthuswamy
> ---
> Changes since v1:
> - Added a sysctl config option to allow the user to control if panic message
> should be reported to Hyper-V.
>
> Changes since v2:
> - Addressed comments from Greg KH.
> - Moved the sysctl config option from 'kernel.hyperv' to 'kernel.' since the
> likelihood of having many Hyper-V specific sysctl config options seemed less
> and so having a specific dir for Hyper-V seemed unnecessary overhead.
>
> Changes since v3:
> - The feature is only enabled if the capability is supported by the
> hypervisor.
> This is done by reading the crash control MSR, in addition to the
> pre-existing
> check for the hypervisor feature using the CPUID.
>
> Changes since v4:
> - Addressed comments from Dexuan Cui: moved the global variable to static.
> ---
> Documentation/sysctl/kernel.txt| 11
> arch/x86/hyperv/hv_init.c | 27 +
> arch/x86/include/asm/hyperv-tlfs.h | 5 +-
> arch/x86/include/asm/mshyperv.h| 1 +
> drivers/hv/vmbus_drv.c | 116
> +
> 5 files changed, 158 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/sysctl/kernel.txt
> b/Documentation/sysctl/kernel.txt
> index eded671d..5958503 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -39,6 +39,7 @@ show up in /proc/sys/kernel:
> - hung_task_check_count
> - hung_task_timeout_secs
> - hung_task_warnings
> +- hyperv_record_panic_msg
> - kexec_load_disabled
> - kptr_restrict
> - l2cr[ PPC only ]
> @@ -374,6 +375,16 @@ This file shows up if CONFIG_DETECT_HUNG_TASK is
> enabled.
>
>
> ==
>
>
> +hyperv_record_panic_msg:
> +
> +Controls whether the panic kmsg data should be reported to Hyper-V.
> +
> +0: do not report panic kmsg data.
> +
> +1: report the panic kmsg data. This is the default behavior.
> +
> +=
> =
> +
> kexec_load_disabled:
>
> A toggle indicating if the kexec_load syscall has been disabled. This
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index cfecc22..af57162 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -395,6 +395,33 @@ void hyperv_report_panic(struct pt_regs *regs, long
> err)
> }
> EXPORT_SYMBOL_GPL(hyperv_report_panic);
>
> +/**
> + * hyperv_report_panic_msg - report panic message to Hyper-V
> + * @pa: physical address of the panic page containing the message
> + * @size: size of the message in the page
> + */
> +void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
> +{
> + /*
> + * P3 to contain the physical address of the panic page & P4 to
> + * contain the size of the panic data in that page. Rest of the
> + * registers are no-op when the NOTIFY_MSG flag is set.
> + */
> + wrmsrl(HV_X64_MSR_CRASH_P0, 0);
> + wrmsrl(HV_X64_MSR_CRASH_P1, 0);
> + wrmsrl(HV_X64_MSR_CRASH_P2, 0);
> + wrmsrl(HV_X64_MSR_CRASH_P3, pa);
> + wrmsrl(HV_X64_MSR_CRASH_P4, size);
> +
> + /*
> + * Let Hyper-V know there is crash data available along with
> + * the panic message.
> + */
> + wrmsrl(HV_X64_MSR_CRASH_CTL,
> +(HV_CRASH_CTL_CRASH_NOTIFY |
> HV_CRASH_CTL_CRASH_NOTIFY_MSG));
> +}
> +EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
> +
> bool hv_is_hyperv_initialized(void)
> {
> union hv_x64_msr_hypercall_contents hypercall_msr;
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h
> b/arch/x86/include/asm/hyperv-tlfs.h
> index 416cb0e..76c58af 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -171,9 +171,10 @@
> #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED(1 << 14)
>
> /*
> - * Crash notification flag.
> + * Crash notification flags.
> */
> -#define HV_CRASH_CTL_CRASH_NOTIFY (1ULL << 63)
> +#define HV_CRASH_CTL_CRASH_NOTIFY_MSGBIT_ULL(62)
> +#define HV_CRASH_CTL_CRASH_NOTIFY
