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From: Frederic Barrat <fbarrat@linux.ibm.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>,
	Leonardo Bras <leobras.c@gmail.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	David Gibson <david@gibson.dropbear.id.au>,
	kernel test robot <lkp@intel.com>,
	Nicolin Chen <nicoleotsuka@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 10/11] powerpc/pseries/iommu: Make use of DDW for indirect mapping
Date: Wed, 21 Jul 2021 17:04:34 +0200	[thread overview]
Message-ID: <994051df-73b3-4dad-76aa-1a03d9afaf6d@linux.ibm.com> (raw)
In-Reply-To: <8dfb28d5-b654-746c-03d8-aeee3d438240@ozlabs.ru>



On 21/07/2021 05:32, Alexey Kardashevskiy wrote:
>>> +        struct iommu_table *newtbl;
>>> +        int i;
>>> +
>>> +        for (i = 0; i < ARRAY_SIZE(pci->phb->mem_resources); i++) {
>>> +            const unsigned long mask = IORESOURCE_MEM_64 | 
>>> IORESOURCE_MEM;
>>> +
>>> +            /* Look for MMIO32 */
>>> +            if ((pci->phb->mem_resources[i].flags & mask) == 
>>> IORESOURCE_MEM)
>>> +                break;
>>> +        }
>>> +
>>> +        if (i == ARRAY_SIZE(pci->phb->mem_resources))
>>> +            goto out_del_list;
>>
>>
>> So we exit and do nothing if there's no MMIO32 bar?
>> Isn't the intent just to figure out the MMIO32 area to reserve it when 
>> init'ing the table? In which case we could default to 0,0
>>
>> I'm actually not clear why we are reserving this area on pseries.
> 
> 
> 
> If we do not reserve it, then the iommu code will allocate DMA pages 
> from there and these addresses are MMIO32 from the kernel pov at least. 
> I saw crashes when (I think) a device tried DMAing to the top 2GB of the 
> bus space which happened to be a some other device's BAR.


hmmm... then figuring out the correct range needs more work. We could 
have more than one MMIO32 bar. And they don't have to be adjacent. I 
don't see that we are reserving any range on the initial table though 
(on pseries).

   Fred

  reply	other threads:[~2021-07-21 15:05 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16  8:27 [PATCH v5 00/11] DDW + Indirect Mapping Leonardo Bras
2021-07-16  8:27 ` [PATCH v5 01/11] powerpc/pseries/iommu: Replace hard-coded page shift Leonardo Bras
2021-07-19 13:48   ` Frederic Barrat
2021-07-19 18:43     ` Leonardo Brás
2021-07-16  8:27 ` [PATCH v5 02/11] powerpc/kernel/iommu: Add new iommu_table_in_use() helper Leonardo Bras
2021-07-19 13:53   ` Frederic Barrat
2021-07-20  5:38     ` Leonardo Brás
2021-07-20  9:41       ` Alexey Kardashevskiy
2021-07-16  8:27 ` [PATCH v5 03/11] powerpc/pseries/iommu: Add iommu_pseries_alloc_table() helper Leonardo Bras
2021-07-19 14:04   ` Frederic Barrat
2021-07-19 18:47     ` Leonardo Brás
2021-07-16  8:27 ` [PATCH v5 04/11] powerpc/pseries/iommu: Add ddw_list_new_entry() helper Leonardo Bras
2021-07-19 14:14   ` Frederic Barrat
2021-07-19 18:47     ` Leonardo Brás
2021-07-16  8:27 ` [PATCH v5 05/11] powerpc/pseries/iommu: Allow DDW windows starting at 0x00 Leonardo Bras
2021-07-20 17:44   ` Frederic Barrat
2021-07-16  8:27 ` [PATCH v5 06/11] powerpc/pseries/iommu: Add ddw_property_create() and refactor enable_ddw() Leonardo Bras
2021-07-20 17:49   ` Frederic Barrat
2021-08-17  5:59     ` Leonardo Brás
2021-07-16  8:27 ` [PATCH v5 07/11] powerpc/pseries/iommu: Reorganize iommu_table_setparms*() with new helper Leonardo Bras
2021-07-20 17:50   ` Frederic Barrat
2021-07-16  8:27 ` [PATCH v5 08/11] powerpc/pseries/iommu: Update remove_dma_window() to accept property name Leonardo Bras
2021-07-20 17:51   ` Frederic Barrat
2021-08-17  5:59     ` Leonardo Brás
2021-08-17  6:12       ` Leonardo Brás
2021-08-24  6:31         ` Alexey Kardashevskiy
2021-07-16  8:27 ` [PATCH v5 09/11] powerpc/pseries/iommu: Find existing DDW with given " Leonardo Bras
2021-07-20 17:52   ` Frederic Barrat
2021-07-16  8:27 ` [PATCH v5 10/11] powerpc/pseries/iommu: Make use of DDW for indirect mapping Leonardo Bras
2021-07-20 18:12   ` Frederic Barrat
2021-07-21  3:32     ` Alexey Kardashevskiy
2021-07-21 15:04       ` Frederic Barrat [this message]
2021-07-23  5:34         ` Alexey Kardashevskiy
2021-08-17  5:59           ` Leonardo Brás
2021-08-17  5:59       ` Leonardo Brás
2021-07-16  8:27 ` [PATCH v5 11/11] powerpc/pseries/iommu: Rename "direct window" to "dma window" Leonardo Bras
2021-07-20 18:12   ` Frederic Barrat

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