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Groups > linux.kernel > #1483858 > unrolled thread
| Started by | "Raslan, KarimAllah" <karahmed@amazon.de> |
|---|---|
| First post | 2016-09-15 08:00 +0200 |
| Last post | 2016-09-15 18:30 +0200 |
| Articles | 4 — 3 participants |
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Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not "Raslan, KarimAllah" <karahmed@amazon.de> - 2016-09-15 08:00 +0200
Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not Paolo Bonzini <pbonzini@redhat.com> - 2016-09-15 08:30 +0200
Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not "Kani, Toshimitsu" <toshi.kani@hpe.com> - 2016-09-15 18:20 +0200
Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not Paolo Bonzini <pbonzini@redhat.com> - 2016-09-15 18:30 +0200
| From | "Raslan, KarimAllah" <karahmed@amazon.de> |
|---|---|
| Date | 2016-09-15 08:00 +0200 |
| Subject | Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not |
| Message-ID | <shxSi-2ZY-3@gated-at.bofh.it> |
> On Jun 22, 2016, at 3:41 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > > > > On 22/06/2016 04:34, KarimAllah Ahmed wrote: >> pfn_valid check is not sufficient because it only checks if a page has a struct >> page or not, if for example "mem=" was passed to the kernel some valid pages >> won't have a struct page. This means that if guests were assigned valid memory >> that lies after the mem= boundary it will be passed uncached to the guest no >> matter what the guest caching attributes are for this memory. > > How can you pass memory after the mem= boundary to the guest? Does my previous reply answer your question? > > Paolo > Amazon Development Center Germany GmbH Berlin - Dresden - Aachen main office: Krausenstr. 38, 10117 Berlin Geschaeftsfuehrer: Dr. Ralf Herbrich, Christian Schlaeger Ust-ID: DE289237879 Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
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| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Date | 2016-09-15 08:30 +0200 |
| Message-ID | <shylj-3ql-5@gated-at.bofh.it> |
| In reply to | #1483858 |
On 15/09/2016 07:54, Raslan, KarimAllah wrote: > >> On Jun 22, 2016, at 3:41 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: >> >> >> >> On 22/06/2016 04:34, KarimAllah Ahmed wrote: >>> pfn_valid check is not sufficient because it only checks if a page has a struct >>> page or not, if for example "mem=" was passed to the kernel some valid pages >>> won't have a struct page. This means that if guests were assigned valid memory >>> that lies after the mem= boundary it will be passed uncached to the guest no >>> matter what the guest caching attributes are for this memory. >> >> How can you pass memory after the mem= boundary to the guest? > > Does my previous reply answer your question? Yes, but I'm not sure it's the right way to do it. Looking at the e820 memory map seems pretty hacky. Paolo
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| From | "Kani, Toshimitsu" <toshi.kani@hpe.com> |
|---|---|
| Date | 2016-09-15 18:20 +0200 |
| Message-ID | <shHyh-SP-5@gated-at.bofh.it> |
| In reply to | #1483866 |
On Thu, 2016-09-15 at 08:22 +0200, Paolo Bonzini wrote: > > On 15/09/2016 07:54, Raslan, KarimAllah wrote: > > > > > > > > > > On Jun 22, 2016, at 3:41 PM, Paolo Bonzini <pbonzini@redhat.com> > > > wrote: > > > > > > > > > > > > On 22/06/2016 04:34, KarimAllah Ahmed wrote: > > > > > > > > pfn_valid check is not sufficient because it only checks if a > > > > page has a struct page or not, if for example "mem=" was passed > > > > to the kernel some valid pages won't have a struct page. This > > > > means that if guests were assigned valid memory that lies after > > > > the mem= boundary it will be passed uncached to the guest no > > > > matter what the guest caching attributes are for this memory. > > > > > > How can you pass memory after the mem= boundary to the guest? > > > > Does my previous reply answer your question? > > Yes, but I'm not sure it's the right way to do it. Looking at the > e820 memory map seems pretty hacky. Can you use region_intersects() for this check? See memremap() as an example using this interface. -Toshi
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| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Date | 2016-09-15 18:30 +0200 |
| Message-ID | <shHHX-Wc-9@gated-at.bofh.it> |
| In reply to | #1484378 |
On 15/09/2016 18:04, Kani, Toshimitsu wrote: > On Thu, 2016-09-15 at 08:22 +0200, Paolo Bonzini wrote: >> >> On 15/09/2016 07:54, Raslan, KarimAllah wrote: >>> >>> >>>> >>>> On Jun 22, 2016, at 3:41 PM, Paolo Bonzini <pbonzini@redhat.com> >>>> wrote: >>>> >>>> >>>> >>>> On 22/06/2016 04:34, KarimAllah Ahmed wrote: >>>>> >>>>> pfn_valid check is not sufficient because it only checks if a >>>>> page has a struct page or not, if for example "mem=" was passed >>>>> to the kernel some valid pages won't have a struct page. This >>>>> means that if guests were assigned valid memory that lies after >>>>> the mem= boundary it will be passed uncached to the guest no >>>>> matter what the guest caching attributes are for this memory. >>>> >>>> How can you pass memory after the mem= boundary to the guest? >>> >>> Does my previous reply answer your question? >> >> Yes, but I'm not sure it's the right way to do it. Looking at the >> e820 memory map seems pretty hacky. > > Can you use region_intersects() for this check? See memremap() as an > example using this interface. This one seems more generic but very slow. Paolo
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