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Date: Thu, 14 May 2020 11:46:52 -0500
From: wenxiong <wenxiong@linux.vnet.ibm.com>
To: Sam Bobroff <sbobroff@linux.ibm.com>
Subject: Re: powerpc/pci: [PATCH 1/1]: PCIE PHB reset
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On 2020-05-12 00:28, Sam Bobroff wrote:
> On Thu, May 07, 2020 at 08:10:37AM -0500, wenxiong@linux.vnet.ibm.com 
> wrote:
>> From: Wen Xiong <wenxiong@linux.vnet.ibm.com>
>> 
>> Several device drivers hit EEH(Extended Error handling) when 
>> triggering
>> kdump on Pseries PowerVM. This patch implemented a reset of the PHBs
>> in pci general code. PHB reset stop all PCI transactions from previous
>> kernel. We have tested the patch in several enviroments:
>> - direct slot adapters
>> - adapters under the switch
>> - a VF adapter in PowerVM
>> - a VF adapter/adapter in KVM guest.
>> 
>> Signed-off-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
> 
> Hi Wen Xiong,
> 
> I saw Oliver's review and I think he's covered the main issues I was
> going to raise:
> - This will run and produce some spurious errors on powernv. (I think
>   distros do compile in both pseries and powernv.)
> - There's a bit of code duplication but it's probably OK for this 
> patch.
> 

Hi Oliver and Sam,

Yes. Thanks for reviewing the code. I will keep some code duplication 
for now until Oliver re-work the EEH code. I am going to fix several 
minor things in error code patch.

Thanks,
Wendy

> I have a few other minor comments, below:
> 
>> ---
>>  arch/powerpc/platforms/pseries/pci.c | 153 
>> +++++++++++++++++++++++++++
>>  1 file changed, 153 insertions(+)
>> 
>> diff --git a/arch/powerpc/platforms/pseries/pci.c 
>> b/arch/powerpc/platforms/pseries/pci.c
>> index 911534b89c85..aac7f00696d2 100644
>> --- a/arch/powerpc/platforms/pseries/pci.c
>> +++ b/arch/powerpc/platforms/pseries/pci.c
>> @@ -11,6 +11,8 @@
>>  #include <linux/kernel.h>
>>  #include <linux/pci.h>
>>  #include <linux/string.h>
>> +#include <linux/crash_dump.h>
>> +#include <linux/delay.h>
>> 
>>  #include <asm/eeh.h>
>>  #include <asm/pci-bridge.h>
>> @@ -354,3 +356,154 @@ int pseries_root_bridge_prepare(struct 
>> pci_host_bridge *bridge)
>> 
>>  	return 0;
>>  }
>> +
>> +/**
>> + * pseries_get_pdn_addr - Retrieve PHB address
>> + * @pe: EEH PE
>> + *
>> + * Retrieve the assocated PHB address. Actually, there're 2 RTAS
>> + * function calls dedicated for the purpose. We need implement
>> + * it through the new function and then the old one. Besides,
>> + * you should make sure the config address is figured out from
>> + * FDT node before calling the function.
>> + *
>> + */
>> +static int pseries_get_pdn_addr(struct pci_controller *phb)
>> +{
>> +	int ret = -1;
>> +	int rets[3];
>> +	int ibm_get_config_addr_info;
>> +	int ibm_get_config_addr_info2;
>> +	int config_addr = 0;
>> +	struct pci_dn *root_pdn, *pdn;
>> +
>> +	ibm_get_config_addr_info2   = 
>> rtas_token("ibm,get-config-addr-info2");
>> +	ibm_get_config_addr_info    = 
>> rtas_token("ibm,get-config-addr-info");
>> +
>> +	root_pdn = PCI_DN(phb->dn);
>> +	pdn = list_first_entry(&root_pdn->child_list, struct pci_dn, list);
>> +	config_addr = (pdn->busno << 16) | (pdn->devfn << 8);
>> +
>> +	if (ibm_get_config_addr_info2 != RTAS_UNKNOWN_SERVICE) {
>> +		/*
>> +		 * First of all, we need to make sure there has one PE
>> +		 * associated with the device. Otherwise, PE address is
>> +		 * meaningless.
>> +		 */
> 
> This comment might be better if it explained how using option=0
> with ibm_get_config_addr tests the PE.
> 
>> +		ret = rtas_call(ibm_get_config_addr_info2, 4, 2, rets,
>> +			config_addr, BUID_HI(pdn->phb->buid),
>> +			BUID_LO(pdn->phb->buid), 1);
>> +		if (ret || (rets[0] == 0)) {
>> +			pr_warn("%s: Failed to get address for PHB#%x-PE# "
>> +				"option=%d config_addr=%x\n",
>> +				__func__, pdn->phb->global_number, 1, rets[0]);
>> +			return -1;
>> +		}
>> +
>> +		/* Retrieve the associated PE config address */
>> +		ret = rtas_call(ibm_get_config_addr_info2, 4, 2, rets,
>> +			config_addr, BUID_HI(pdn->phb->buid),
>> +			BUID_LO(pdn->phb->buid), 0);
>> +		if (ret) {
>> +			pr_warn("%s: Failed to get address for PHB#%x-PE# "
>> +				"option=%d config_addr=%x\n",
>> +				__func__, pdn->phb->global_number, 0, rets[0]);
>> +			return -1;
>> +		}
>> +		return rets[0];
>> +	}
>> +
>> +	if (ibm_get_config_addr_info != RTAS_UNKNOWN_SERVICE) {
>> +		ret = rtas_call(ibm_get_config_addr_info, 4, 2, rets,
>> +			config_addr, BUID_HI(pdn->phb->buid),
>> +			BUID_LO(pdn->phb->buid), 0);
>> +		if (ret || rets[0]) {
>> +			pr_warn("%s: Failed to get address for PHB#%x-PE# "
>> +				"config_addr=%x\n",
>> +				__func__, pdn->phb->global_number, rets[0]);
>> +			return -1;
>> +		}
>> +		return rets[0];
>> +	}
>> +
>> +	return ret;
> Can this ever return anything other than 0?
> 
>> +}
>> +
>> +static int __init pseries_phb_reset(void)
>> +{
>> +	struct pci_controller *phb;
>> +	int config_addr;
>> +	int ibm_set_slot_reset;
>> +	int ibm_configure_pe;
>> +	int ret;
>> +
>> +	if (is_kdump_kernel() || reset_devices) {
>> +		pr_info("Issue PHB reset ...\n");
>> +		ibm_set_slot_reset = rtas_token("ibm,set-slot-reset");
>> +		ibm_configure_pe = rtas_token("ibm,configure-pe");
>> +
>> +		if (ibm_set_slot_reset == RTAS_UNKNOWN_SERVICE ||
>> +				ibm_configure_pe == RTAS_UNKNOWN_SERVICE) {
>> +			pr_info("%s: EEH functionality not supported\n",
>> +				__func__);
>> +		}
>> +
>> +		list_for_each_entry(phb, &hose_list, list_node) {
>> +			config_addr = pseries_get_pdn_addr(phb);
>> +			if (config_addr == -1)
>> +				continue;
>> +
>> +			ret = rtas_call(ibm_set_slot_reset, 4, 1, NULL,
>> +				config_addr, BUID_HI(phb->buid),
>> +				BUID_LO(phb->buid), EEH_RESET_FUNDAMENTAL);
>> +
>> +			/* If fundamental-reset not supported, try hot-reset */
>> +			if (ret == -8)
>> +				ret = rtas_call(ibm_set_slot_reset, 4, 1, NULL,
>> +					config_addr, BUID_HI(phb->buid),
>> +					BUID_LO(phb->buid), EEH_RESET_HOT);
>> +
>> +			if (ret) {
>> +				pr_err("%s: fail with rtas_call fundamental reset=%d\n",
>> +					__func__, ret);
> 
> This error might be a bit confusing, since it's not clear if the result
> came from the fundamental or hot-reset.
> 
>> +				continue;
>> +			}
>> +		}
>> +		msleep(EEH_PE_RST_SETTLE_TIME);
>> +
>> +		list_for_each_entry(phb, &hose_list, list_node) {
>> +			config_addr = pseries_get_pdn_addr(phb);
>> +			if (config_addr == -1)
>> +				continue;
>> +
>> +			ret = rtas_call(ibm_set_slot_reset, 4, 1, NULL,
>> +				config_addr, BUID_HI(phb->buid),
>> +				BUID_LO(phb->buid), EEH_RESET_DEACTIVATE);
>> +			if (ret) {
>> +				pr_err("%s: fail with rtas_call deactive=%d\n",
>> +					__func__, ret);
>> +				continue;
>> +			}
>> +		}
>> +		msleep(EEH_PE_RST_SETTLE_TIME);
>> +
>> +		list_for_each_entry(phb, &hose_list, list_node) {
>> +			config_addr = pseries_get_pdn_addr(phb);
>> +			if (config_addr == -1)
>> +				continue;
>> +
>> +			ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
>> +				config_addr, BUID_HI(phb->buid),
>> +				BUID_LO(phb->buid));
>> +			if (ret) {
>> +				pr_err("%s: fail with rtas_call configure_pe =%d\n",
>> +					__func__, ret);
> 
> These errors might be more useful if they indicated which PHB caused 
> the
> error.
> 
>> +				continue;
>> +			}
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +postcore_initcall(pseries_phb_reset);
>> +
>> --
>> 2.18.1
>>