From: "Zhang,Yi" <yi.z.zhang@linux.intel.com>
To: "Pankaj Gupta" <pagupta@redhat.com>,
"Jérôme Glisse" <jglisse@redhat.com>
Cc: jack@suse.cz, yu c zhang <yu.c.zhang@intel.com>,
kvm@vger.kernel.org, linux-nvdimm@lists.01.org,
rkrcmar@redhat.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, pbonzini@redhat.com, hch@lst.de,
yi z zhang <yi.z.zhang@intel.com>
Subject: Re: [PATCH V3 3/4] mm: add a function to differentiate the pages is from DAX device memory
Date: Tue, 14 Aug 2018 01:41:40 +0800 [thread overview]
Message-ID: <5ea50e63-b55a-c1e1-50be-6e2d951c04cf@linux.intel.com> (raw)
In-Reply-To: <872818364.892078.1533806608252.JavaMail.zimbra@redhat.com>
On 2018年08月09日 17:23, Pankaj Gupta wrote:
>> DAX driver hotplug the device memory and move it to memory zone, these
>> pages will be marked reserved flag, however, some other kernel componet
>> will misconceive these pages are reserved mmio (ex: we map these dev_dax
>> or fs_dax pages to kvm for DIMM/NVDIMM backend). Together with the type
>> MEMORY_DEVICE_FS_DAX, we can use is_dax_page() to differentiate the pages
>> is DAX device memory or not.
>>
>> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
>> Signed-off-by: Zhang Yu <yu.c.zhang@linux.intel.com>
>> ---
>> include/linux/mm.h | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index 68a5121..de5cbc3 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -889,6 +889,13 @@ static inline bool is_device_public_page(const struct
>> page *page)
>> page->pgmap->type == MEMORY_DEVICE_PUBLIC;
>> }
>>
>> +static inline bool is_dax_page(const struct page *page)
>> +{
>> + return is_zone_device_page(page) &&
>> + (page->pgmap->type == MEMORY_DEVICE_FS_DAX ||
>> + page->pgmap->type == MEMORY_DEVICE_DEV_DAX);
>> +}
> I think question from Dan for KVM VM with 'MEMORY_DEVICE_PUBLIC' still holds?
> I am also interested to know if there is any use-case.
>
> Thanks,
> Pankaj
Yes, it is, thanks for your remind, Pankaj.
Adding Jerome for Dan's questions on V1:
[Dan]:
Jerome, might there be any use case to pass MEMORY_DEVICE_PUBLIC
memory to a guest vm?
>
>> +
>> #else /* CONFIG_DEV_PAGEMAP_OPS */
>> static inline void dev_pagemap_get_ops(void)
>> {
>> @@ -912,6 +919,11 @@ static inline bool is_device_public_page(const struct
>> page *page)
>> {
>> return false;
>> }
>> +
>> +static inline bool is_dax_page(const struct page *page)
>> +{
>> + return false;
>> +}
>> #endif /* CONFIG_DEV_PAGEMAP_OPS */
>>
>> static inline void get_page(struct page *page)
>> --
>> 2.7.4
>>
>>
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next prev parent reply other threads:[~2018-08-13 9:57 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-09 10:52 [PATCH V3 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio Zhang Yi
2018-08-09 9:02 ` Jan Kara
2018-08-13 17:33 ` Zhang,Yi
2018-08-09 10:52 ` [PATCH V3 1/4] kvm: remove redundant reserved page check Zhang Yi
2018-08-09 9:13 ` Pankaj Gupta
2018-08-10 11:23 ` David Hildenbrand
2018-08-09 10:53 ` [PATCH V3 2/4] mm: introduce memory type MEMORY_DEVICE_DEV_DAX Zhang Yi
2018-08-09 8:59 ` Jan Kara
2018-08-09 10:53 ` [PATCH V3 3/4] mm: add a function to differentiate the pages is from DAX device memory Zhang Yi
2018-08-09 9:23 ` Pankaj Gupta
2018-08-13 17:41 ` Zhang,Yi [this message]
2018-08-13 14:29 ` Jerome Glisse
2018-08-09 10:53 ` [PATCH V3 4/4] kvm: add a check if pfn is from NVDIMM pmem Zhang Yi
2018-08-09 8:32 ` Pankaj Gupta
2018-08-13 17:32 ` Zhang,Yi
2018-08-10 13:27 ` [PATCH V3 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio David Hildenbrand
2018-08-13 17:25 ` Zhang,Yi
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