From: yulei zhang <yulei.kernel@gmail.com>
To: Joao Martins <joao.m.martins@oracle.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
akpm@linux-foundation.org, naoya.horiguchi@nec.com,
viro@zeniv.linux.org.uk, Paolo Bonzini <pbonzini@redhat.com>,
linux-fsdevel@vger.kernel.org, kvm <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Haiwei Li <lihaiwei.kernel@gmail.com>,
Yulei Zhang <yuleixzhang@tencent.com>,
Chen Zhuo <sagazchen@tencent.com>
Subject: Re: [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page
Date: Fri, 9 Oct 2020 19:42:17 +0800 [thread overview]
Message-ID: <CACZOiM2W_8P_S6EypD3XfX1RuU+Do69w9qEMk7nDH2BxtK2E1g@mail.gmail.com> (raw)
In-Reply-To: <a6dd5fbe-ca71-cf05-ec40-ec916843e9b7@oracle.com>
Sean and Joao, thanks for the feedback. Probably we can drop this change.
On Fri, Oct 9, 2020 at 6:28 PM Joao Martins <joao.m.martins@oracle.com> wrote:
>
> On 10/9/20 1:58 AM, Sean Christopherson wrote:
> > On Thu, Oct 08, 2020 at 03:54:12PM +0800, yulei.kernel@gmail.com wrote:
> >> From: Yulei Zhang <yuleixzhang@tencent.com>
> >>
> >> Dmem page is pfn invalid but not mmio. Support cacheable
> >> dmem page for kvm.
> >>
> >> Signed-off-by: Chen Zhuo <sagazchen@tencent.com>
> >> Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
> >> ---
> >> arch/x86/kvm/mmu/mmu.c | 5 +++--
> >> include/linux/dmem.h | 7 +++++++
> >> mm/dmem.c | 7 +++++++
> >> 3 files changed, 17 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> >> index 71aa3da2a0b7..0115c1767063 100644
> >> --- a/arch/x86/kvm/mmu/mmu.c
> >> +++ b/arch/x86/kvm/mmu/mmu.c
> >> @@ -41,6 +41,7 @@
> >> #include <linux/hash.h>
> >> #include <linux/kern_levels.h>
> >> #include <linux/kthread.h>
> >> +#include <linux/dmem.h>
> >>
> >> #include <asm/page.h>
> >> #include <asm/memtype.h>
> >> @@ -2962,9 +2963,9 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
> >> */
> >> (!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn));
> >>
> >> - return !e820__mapped_raw_any(pfn_to_hpa(pfn),
> >> + return (!e820__mapped_raw_any(pfn_to_hpa(pfn),
> >> pfn_to_hpa(pfn + 1) - 1,
> >> - E820_TYPE_RAM);
> >> + E820_TYPE_RAM)) || (!is_dmem_pfn(pfn));
> >
> > This is wrong. As is, the logic reads "A PFN is MMIO if it is INVALID &&
> > (!RAM || !DMEM)". The obvious fix would be to change it to "INVALID &&
> > !RAM && !DMEM", but that begs the question of whether or DMEM is reported
> > as RAM. I don't see any e820 related changes in the series, i.e. no evidence
> > that dmem yanks its memory out of the e820 tables, which makes me think this
> > change is unnecessary.
> >
> Even if there would exist e820 changes, e820__mapped_raw_any() checks against
> hardware-provided e820 that we are given before any changes happen i.e. not the one kernel
> has changed (e820_table_firmware). So unless you're having that memory carved from an MMIO
> range (which would be wrong), or the BIOS is misrepresenting its memory map... the
> e820__mapped_raw_any(E820_TYPE_RAM) ought to be enough to cover RAM.
>
> Or at least that has been my experience with similar work.
>
> Joao
next prev parent reply other threads:[~2020-10-09 11:42 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 7:53 [PATCH 00/35] Enhance memory utilization with DMEMFS yulei.kernel
2020-10-08 7:53 ` [PATCH 01/35] fs: introduce dmemfs module yulei.kernel
2020-11-10 20:04 ` Al Viro
2020-11-11 8:53 ` yulei zhang
2020-11-11 23:09 ` Al Viro
2020-11-12 10:03 ` yulei zhang
2020-10-08 7:53 ` [PATCH 02/35] mm: support direct memory reservation yulei.kernel
2020-10-08 20:27 ` Randy Dunlap
2020-10-08 20:34 ` Randy Dunlap
2020-10-08 7:53 ` [PATCH 03/35] dmem: implement dmem memory management yulei.kernel
2020-10-08 7:53 ` [PATCH 04/35] dmem: let pat recognize dmem yulei.kernel
2020-10-13 7:27 ` Paolo Bonzini
2020-10-13 9:53 ` yulei zhang
2020-10-08 7:53 ` [PATCH 05/35] dmemfs: support mmap yulei.kernel
2020-10-08 7:53 ` [PATCH 06/35] dmemfs: support truncating inode down yulei.kernel
2020-10-08 7:53 ` [PATCH 07/35] dmem: trace core functions yulei.kernel
2020-10-08 7:53 ` [PATCH 08/35] dmem: show some statistic in debugfs yulei.kernel
2020-10-08 20:23 ` Randy Dunlap
2020-10-09 11:49 ` yulei zhang
2020-10-08 7:53 ` [PATCH 09/35] dmemfs: support remote access yulei.kernel
2020-10-08 7:54 ` [PATCH 10/35] dmemfs: introduce max_alloc_try_dpages parameter yulei.kernel
2020-10-08 7:54 ` [PATCH 11/35] mm: export mempolicy interfaces to serve dmem allocator yulei.kernel
2020-10-08 7:54 ` [PATCH 12/35] dmem: introduce mempolicy support yulei.kernel
2020-10-08 7:54 ` [PATCH 13/35] mm, dmem: introduce PFN_DMEM and pfn_t_dmem yulei.kernel
2020-10-08 7:54 ` [PATCH 14/35] mm, dmem: dmem-pmd vs thp-pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 15/35] mm: add pmd_special() check for pmd_trans_huge_lock() yulei.kernel
2020-10-08 7:54 ` [PATCH 16/35] dmemfs: introduce ->split() to dmemfs_vm_ops yulei.kernel
2020-10-08 7:54 ` [PATCH 17/35] mm, dmemfs: support unmap_page_range() for dmemfs pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 18/35] mm: follow_pmd_mask() for dmem huge pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 19/35] mm: gup_huge_pmd() " yulei.kernel
2020-10-08 7:54 ` [PATCH 20/35] mm: support dmem huge pmd for vmf_insert_pfn_pmd() yulei.kernel
2020-10-08 7:54 ` [PATCH 21/35] mm: support dmem huge pmd for follow_pfn() yulei.kernel
2020-10-08 7:54 ` [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page yulei.kernel
2020-10-09 0:58 ` Sean Christopherson
2020-10-09 10:28 ` Joao Martins
2020-10-09 11:42 ` yulei zhang [this message]
2020-10-08 7:54 ` [PATCH 23/35] kvm, x86: introduce VM_DMEM yulei.kernel
2020-10-08 7:54 ` [PATCH 24/35] dmemfs: support hugepage for dmemfs yulei.kernel
2020-10-08 7:54 ` [PATCH 25/35] mm, x86, dmem: fix estimation of reserved page for vaddr_get_pfn() yulei.kernel
2020-10-08 7:54 ` [PATCH 26/35] mm, dmem: introduce pud_special() yulei.kernel
2020-10-08 7:54 ` [PATCH 27/35] mm: add pud_special() to support dmem huge pud yulei.kernel
2020-10-08 7:54 ` [PATCH 28/35] mm, dmemfs: support huge_fault() for dmemfs yulei.kernel
2020-10-08 7:54 ` [PATCH 29/35] mm: add follow_pte_pud() yulei.kernel
2020-10-08 7:54 ` [PATCH 30/35] dmem: introduce dmem_bitmap_alloc() and dmem_bitmap_free() yulei.kernel
2020-10-08 7:54 ` [PATCH 31/35] dmem: introduce mce handler yulei.kernel
2020-10-08 7:54 ` [PATCH 32/35] mm, dmemfs: register and handle the dmem mce yulei.kernel
2020-10-08 7:54 ` [PATCH 33/35] kvm, x86: temporary disable record_steal_time for dmem yulei.kernel
2020-10-08 7:54 ` [PATCH 34/35] dmem: add dmem unit tests yulei.kernel
2020-10-08 7:54 ` [PATCH 35/35] Add documentation for dmemfs yulei.kernel
2020-10-09 1:26 ` Randy Dunlap
2020-10-08 19:01 ` [PATCH 00/35] Enhance memory utilization with DMEMFS Joao Martins
2020-10-09 11:39 ` yulei zhang
2020-10-09 11:53 ` Joao Martins
2020-10-10 8:15 ` yulei zhang
2020-10-12 10:59 ` Joao Martins
2020-10-14 22:25 ` Dan Williams
2020-10-19 13:37 ` Paolo Bonzini
2020-10-19 19:03 ` Joao Martins
2020-10-20 15:22 ` yulei zhang
2020-10-12 11:57 ` Zengtao (B)
2020-10-13 2:45 ` yulei zhang
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