lkml.org 
[lkml]   [2021]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 3/4] KVM: X86: Use smp_rmb() to pair with smp_wmb() in mmu_try_to_unsync_pages()
    From
    Date
    Hello Junaid Shahid

    Any comments on the patch? I may have been misunderstanding many things and I
    have been often.

    thanks
    Lai

    On 2021/10/19 19:01, Lai Jiangshan wrote:
    > From: Lai Jiangshan <laijs@linux.alibaba.com>
    >
    > The commit 578e1c4db2213 ("kvm: x86: Avoid taking MMU lock in
    > kvm_mmu_sync_roots if no sync is needed") added smp_wmb() in
    > mmu_try_to_unsync_pages(), but the corresponding smp_load_acquire()
    > isn't used on the load of SPTE.W which is impossible since the load of
    > SPTE.W is performed in the CPU's pagetable walking.
    >
    > This patch changes to use smp_rmb() instead. This patch fixes nothing
    > but just comments since smp_rmb() is NOP and compiler barrier() is not
    > required since the load of SPTE.W is before VMEXIT.
    >
    > Cc: Junaid Shahid <junaids@google.com>
    > Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>

    \
     
     \ /
      Last update: 2021-10-21 04:33    [W:5.862 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site