[PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Guilherme G. Piccoli]

During a kdump kernel boot in PowerPC, we request a reset of the PHBs
to the FW. It makes sense, since if we are booting a kdump kernel it
means we had some trouble before and we cannot rely in the adapters'
health; they could be in a bad state, hence the reset is needed.

But this reset is useful not only in kdump - there are situations,
specially when debugging drivers, that we could break an adapter in
a way it requires such reset. One can tell to just go ahead and
reboot the machine, but happens that many times doing kexec is much
faster, and so preferable than a full power cycle.

This patch adds the pci_reset_phbs parameter to perform such reset
when desired by the user.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
---
v2: changed name of the parameter [ben/mpe suggestion].

The patch was implemented against powerpc/next.

 arch/powerpc/platforms/powernv/pci-ioda.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index fb5cd7511189..6070e0d4a7f3 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -89,6 +89,7 @@ void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
 }
 
 static bool pnv_iommu_bypass_disabled __read_mostly;
+static bool pci_reset_phbs __read_mostly;
 
 static int __init iommu_setup(char *str)
 {
@@ -110,6 +111,14 @@ static int __init iommu_setup(char *str)
 }
 early_param("iommu", iommu_setup);
 
+static int __init pci_reset_phbs_setup(char *str)
+{
+	pci_reset_phbs = true;
+	return 0;
+}
+
+early_param("pci_reset_phbs", pci_reset_phbs_setup);
+
 static inline bool pnv_pci_is_m64(struct pnv_phb *phb, struct resource *r)
 {
 	/*
@@ -4014,9 +4023,10 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 	 * If we're running in kdump kernel, the previous kernel never
 	 * shutdown PCI devices correctly. We already got IODA table
 	 * cleaned out. So we have to issue PHB reset to stop all PCI
-	 * transactions from previous kernel.
+	 * transactions from previous kernel. The pci_reset_phbs
+	 * kernel parameter will force this reset too.
 	 */
-	if (is_kdump_kernel()) {
+	if (is_kdump_kernel() || pci_reset_phbs) {
 		pr_info("  Issue PHB reset ...\n");
 		pnv_eeh_phb_reset(hose, EEH_RESET_FUNDAMENTAL);
 		pnv_eeh_phb_reset(hose, EEH_RESET_DEACTIVATE);
-- 
2.15.0.rc0

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Guilherme G. Piccoli]

On 10/25/2017 01:27 PM, Guilherme G. Piccoli wrote:
> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
> to the FW. It makes sense, since if we are booting a kdump kernel it
> means we had some trouble before and we cannot rely in the adapters'
> health; they could be in a bad state, hence the reset is needed.
> 
> But this reset is useful not only in kdump - there are situations,
> specially when debugging drivers, that we could break an adapter in
> a way it requires such reset. One can tell to just go ahead and
> reboot the machine, but happens that many times doing kexec is much
> faster, and so preferable than a full power cycle.
> 
> This patch adds the pci_reset_phbs parameter to perform such reset
> when desired by the user.
> 
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
> ---
> v2: changed name of the parameter [ben/mpe suggestion].
> 
> The patch was implemented against powerpc/next.


Hi Michael/Ben...any thoughts about this one?
Thanks in advance!


> 
>  arch/powerpc/platforms/powernv/pci-ioda.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index fb5cd7511189..6070e0d4a7f3 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -89,6 +89,7 @@ void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
>  }
> 
>  static bool pnv_iommu_bypass_disabled __read_mostly;
> +static bool pci_reset_phbs __read_mostly;
> 
>  static int __init iommu_setup(char *str)
>  {
> @@ -110,6 +111,14 @@ static int __init iommu_setup(char *str)
>  }
>  early_param("iommu", iommu_setup);
> 
> +static int __init pci_reset_phbs_setup(char *str)
> +{
> +	pci_reset_phbs = true;
> +	return 0;
> +}
> +
> +early_param("pci_reset_phbs", pci_reset_phbs_setup);
> +
>  static inline bool pnv_pci_is_m64(struct pnv_phb *phb, struct resource *r)
>  {
>  	/*
> @@ -4014,9 +4023,10 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
>  	 * If we're running in kdump kernel, the previous kernel never
>  	 * shutdown PCI devices correctly. We already got IODA table
>  	 * cleaned out. So we have to issue PHB reset to stop all PCI
> -	 * transactions from previous kernel.
> +	 * transactions from previous kernel. The pci_reset_phbs
> +	 * kernel parameter will force this reset too.
>  	 */
> -	if (is_kdump_kernel()) {
> +	if (is_kdump_kernel() || pci_reset_phbs) {
>  		pr_info("  Issue PHB reset ...\n");
>  		pnv_eeh_phb_reset(hose, EEH_RESET_FUNDAMENTAL);
>  		pnv_eeh_phb_reset(hose, EEH_RESET_DEACTIVATE);
> 

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Michael Ellerman]

"Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> writes:

> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
> to the FW. It makes sense, since if we are booting a kdump kernel it
> means we had some trouble before and we cannot rely in the adapters'
> health; they could be in a bad state, hence the reset is needed.
>
> But this reset is useful not only in kdump - there are situations,
> specially when debugging drivers, that we could break an adapter in
> a way it requires such reset. One can tell to just go ahead and
> reboot the machine, but happens that many times doing kexec is much
> faster, and so preferable than a full power cycle.
>
> This patch adds the pci_reset_phbs parameter to perform such reset
> when desired by the user.
>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
> ---
> v2: changed name of the parameter [ben/mpe suggestion].
>
> The patch was implemented against powerpc/next.
>
>  arch/powerpc/platforms/powernv/pci-ioda.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index fb5cd7511189..6070e0d4a7f3 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -89,6 +89,7 @@ void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
>  }
>  
>  static bool pnv_iommu_bypass_disabled __read_mostly;
> +static bool pci_reset_phbs __read_mostly;
>  
>  static int __init iommu_setup(char *str)
>  {
> @@ -110,6 +111,14 @@ static int __init iommu_setup(char *str)
>  }
>  early_param("iommu", iommu_setup);
>  
> +static int __init pci_reset_phbs_setup(char *str)
> +{
> +	pci_reset_phbs = true;
> +	return 0;
> +}
> +
> +early_param("pci_reset_phbs", pci_reset_phbs_setup);

Is there a reason you didn't make it a module parameter?

That is preferable IMHO because it is namespaced, which means we don't
need to worry about polluting the top-level parameter namespace.

cheers

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Balbir Singh]

On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
<gpiccoli@linux.vnet.ibm.com> wrote:
> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
> to the FW. It makes sense, since if we are booting a kdump kernel it
> means we had some trouble before and we cannot rely in the adapters'
> health; they could be in a bad state, hence the reset is needed.
>
> But this reset is useful not only in kdump - there are situations,
> specially when debugging drivers, that we could break an adapter in
> a way it requires such reset. One can tell to just go ahead and
> reboot the machine, but happens that many times doing kexec is much
> faster, and so preferable than a full power cycle.
>
> This patch adds the pci_reset_phbs parameter to perform such reset
> when desired by the user.
>

Do we care to reset specific phbs or all of them? I guess all based on
your description.

Balbir Singh.

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Guilherme G. Piccoli]

On 11/16/2017 01:49 AM, Balbir Singh wrote:
> On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
> <gpiccoli@linux.vnet.ibm.com> wrote:
>> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
>> to the FW. It makes sense, since if we are booting a kdump kernel it
>> means we had some trouble before and we cannot rely in the adapters'
>> health; they could be in a bad state, hence the reset is needed.
>>
>> But this reset is useful not only in kdump - there are situations,
>> specially when debugging drivers, that we could break an adapter in
>> a way it requires such reset. One can tell to just go ahead and
>> reboot the machine, but happens that many times doing kexec is much
>> faster, and so preferable than a full power cycle.
>>
>> This patch adds the pci_reset_phbs parameter to perform such reset
>> when desired by the user.
>>
> 
> Do we care to reset specific phbs or all of them? I guess all based on
> your description.

Exactly Balbir, it does reset all of them. We could add such
granularity, but I don't see much usability..
But if somebody feels it's useful, we can change...

Thanks!


> 
> Balbir Singh.
> 

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Balbir Singh]

On Thu, Nov 16, 2017 at 11:14 PM, Guilherme G. Piccoli
<gpiccoli@linux.vnet.ibm.com> wrote:
> On 11/16/2017 01:49 AM, Balbir Singh wrote:
>> On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
>> <gpiccoli@linux.vnet.ibm.com> wrote:
>>> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
>>> to the FW. It makes sense, since if we are booting a kdump kernel it
>>> means we had some trouble before and we cannot rely in the adapters'
>>> health; they could be in a bad state, hence the reset is needed.
>>>
>>> But this reset is useful not only in kdump - there are situations,
>>> specially when debugging drivers, that we could break an adapter in
>>> a way it requires such reset. One can tell to just go ahead and
>>> reboot the machine, but happens that many times doing kexec is much
>>> faster, and so preferable than a full power cycle.
>>>
>>> This patch adds the pci_reset_phbs parameter to perform such reset
>>> when desired by the user.
>>>
>>
>> Do we care to reset specific phbs or all of them? I guess all based on
>> your description.
>
> Exactly Balbir, it does reset all of them. We could add such
> granularity, but I don't see much usability..
> But if somebody feels it's useful, we can change...
>

OK.. makes sense, any reason why this can't be folded into reset_devices?
I guess we want reset_phbs to be independent of reset_devices

Balbir

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Guilherme G. Piccoli]

On 11/21/2017 12:35 AM, Balbir Singh wrote:
> On Thu, Nov 16, 2017 at 11:14 PM, Guilherme G. Piccoli
> <gpiccoli@linux.vnet.ibm.com> wrote:
>> On 11/16/2017 01:49 AM, Balbir Singh wrote:
>>> On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
>>> <gpiccoli@linux.vnet.ibm.com> wrote:
>>>> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
>>>> to the FW. It makes sense, since if we are booting a kdump kernel it
>>>> means we had some trouble before and we cannot rely in the adapters'
>>>> health; they could be in a bad state, hence the reset is needed.
>>>>
>>>> But this reset is useful not only in kdump - there are situations,
>>>> specially when debugging drivers, that we could break an adapter in
>>>> a way it requires such reset. One can tell to just go ahead and
>>>> reboot the machine, but happens that many times doing kexec is much
>>>> faster, and so preferable than a full power cycle.
>>>>
>>>> This patch adds the pci_reset_phbs parameter to perform such reset
>>>> when desired by the user.
>>>>
>>>
>>> Do we care to reset specific phbs or all of them? I guess all based on
>>> your description.
>>
>> Exactly Balbir, it does reset all of them. We could add such
>> granularity, but I don't see much usability..
>> But if somebody feels it's useful, we can change...
>>
> 
> OK.. makes sense, any reason why this can't be folded into reset_devices?
> I guess we want reset_phbs to be independent of reset_devices

It was, in v1. But mpe asked it to be a powerpc specific parameter heheh
Cheers,


Guilherme

> 
> Balbir
> 

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Michael Ellerman]

"Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> writes:

> On 11/21/2017 12:35 AM, Balbir Singh wrote:
>> On Thu, Nov 16, 2017 at 11:14 PM, Guilherme G. Piccoli
>> <gpiccoli@linux.vnet.ibm.com> wrote:
>>> On 11/16/2017 01:49 AM, Balbir Singh wrote:
>>>> On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
>>>> <gpiccoli@linux.vnet.ibm.com> wrote:
>>>>> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
>>>>> to the FW. It makes sense, since if we are booting a kdump kernel it
>>>>> means we had some trouble before and we cannot rely in the adapters'
>>>>> health; they could be in a bad state, hence the reset is needed.
>>>>>
>>>>> But this reset is useful not only in kdump - there are situations,
>>>>> specially when debugging drivers, that we could break an adapter in
>>>>> a way it requires such reset. One can tell to just go ahead and
>>>>> reboot the machine, but happens that many times doing kexec is much
>>>>> faster, and so preferable than a full power cycle.
>>>>>
>>>>> This patch adds the pci_reset_phbs parameter to perform such reset
>>>>> when desired by the user.
>>>>>
>>>>
>>>> Do we care to reset specific phbs or all of them? I guess all based on
>>>> your description.
>>>
>>> Exactly Balbir, it does reset all of them. We could add such
>>> granularity, but I don't see much usability..
>>> But if somebody feels it's useful, we can change...
>>>
>> 
>> OK.. makes sense, any reason why this can't be folded into reset_devices?
>> I guess we want reset_phbs to be independent of reset_devices
>
> It was, in v1. But mpe asked it to be a powerpc specific parameter heheh

LOL. Turtles.

I still feel like we shouldn't be creating a generically named parameter
like this, though we have done it many times in the past.

Can we call it "ppc_reset_phbs". And then I'll merge it without further
quibbling, honest.

cheers

Re: [PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

[Guilherme G. Piccoli]

On 12/08/2017 10:03 AM, Michael Ellerman wrote:
> "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> writes:
> 
>> On 11/21/2017 12:35 AM, Balbir Singh wrote:
>>> On Thu, Nov 16, 2017 at 11:14 PM, Guilherme G. Piccoli
>>> <gpiccoli@linux.vnet.ibm.com> wrote:
>>>> On 11/16/2017 01:49 AM, Balbir Singh wrote:
>>>>> On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
>>>>> <gpiccoli@linux.vnet.ibm.com> wrote:
>>>>>> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
>>>>>> to the FW. It makes sense, since if we are booting a kdump kernel it
>>>>>> means we had some trouble before and we cannot rely in the adapters'
>>>>>> health; they could be in a bad state, hence the reset is needed.
>>>>>>
>>>>>> But this reset is useful not only in kdump - there are situations,
>>>>>> specially when debugging drivers, that we could break an adapter in
>>>>>> a way it requires such reset. One can tell to just go ahead and
>>>>>> reboot the machine, but happens that many times doing kexec is much
>>>>>> faster, and so preferable than a full power cycle.
>>>>>>
>>>>>> This patch adds the pci_reset_phbs parameter to perform such reset
>>>>>> when desired by the user.
>>>>>>
>>>>>
>>>>> Do we care to reset specific phbs or all of them? I guess all based on
>>>>> your description.
>>>>
>>>> Exactly Balbir, it does reset all of them. We could add such
>>>> granularity, but I don't see much usability..
>>>> But if somebody feels it's useful, we can change...
>>>>
>>>
>>> OK.. makes sense, any reason why this can't be folded into reset_devices?
>>> I guess we want reset_phbs to be independent of reset_devices
>>
>> It was, in v1. But mpe asked it to be a powerpc specific parameter heheh
> 
> LOL. Turtles.
> 
> I still feel like we shouldn't be creating a generically named parameter
> like this, though we have done it many times in the past.
> 
> Can we call it "ppc_reset_phbs". And then I'll merge it without further
> quibbling, honest.

hahah sure! How about this one:  https://patchwork.ozlabs.org/patch/839123

Let me know your thoughts!
Cheers,


Guilherme
> 
> cheers
>