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Subject: Re: [PATCH 3/3] nvme-pci: align CMB size according to P2PMEM
 alignment
To:     Keith Busch <kbusch@kernel.org>
CC:     <linux-nvme@lists.infradead.org>, <dan.j.williams@intel.com>,
        <logang@deltatee.com>, <linux-mm@kvack.org>, <hch@lst.de>,
        <sagi@grimberg.me>, <david@redhat.com>, <oren@nvidia.com>,
        <linux-kernel@vger.kernel.org>, <akpm@linux-foundation.org>
References: <20210602111055.10480-1-mgurtovoy@nvidia.com>
 <20210602111055.10480-4-mgurtovoy@nvidia.com>
 <20210602143940.GA5751@dhcp-10-100-145-180.wdc.com>
From:   Max Gurtovoy <mgurtovoy@nvidia.com>
Message-ID: <9ff88c55-2e9c-3cec-81a5-b47b344815a4@nvidia.com>
Date:   Wed, 2 Jun 2021 17:51:05 +0300
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On 6/2/2021 5:39 PM, Keith Busch wrote:
> On Wed, Jun 02, 2021 at 02:10:55PM +0300, Max Gurtovoy wrote:
>> P2PMEM is using mhp framework to connect to the memory subsystem. In
>> case the CMB size is not compatible to mhp alignment, the CMB mapping
>> will fail. Use pci_p2pdma_align_size to align CMB size in order to
>> successfully map non-aligned original CMB.
>>
>> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
>> ---
>>   drivers/nvme/host/pci.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
>> index a29b170701fc..1197263b4cd0 100644
>> --- a/drivers/nvme/host/pci.c
>> +++ b/drivers/nvme/host/pci.c
>> @@ -1817,6 +1817,7 @@ static void nvme_map_cmb(struct nvme_dev *dev)
>>   	u64 size, offset;
>>   	resource_size_t bar_size;
>>   	struct pci_dev *pdev = to_pci_dev(dev->dev);
>> +	unsigned long nr_pages, min_align;
> These new variables don't appear to be used anywhere.

oh, I have some leftovers..

Sorry.


>
>>   	int bar;
>>   
>>   	if (dev->cmb_size)
>> @@ -1856,6 +1857,12 @@ static void nvme_map_cmb(struct nvme_dev *dev)
>>   	if (size > bar_size - offset)
>>   		size = bar_size - offset;
>>   
>> +	size = pci_p2pdma_align_size(size);
>> +	if (!size) {
>> +		dev_warn(dev->ctrl.device, "CMB size is 0 after alignment\n");
>> +		return;
>> +	}
>> +
>>   	if (pci_p2pdma_add_resource(pdev, bar, size, offset)) {
>>   		dev_warn(dev->ctrl.device,
>>   			 "failed to register the CMB\n");
>> --