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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
next prev parent 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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