Re: [RFC PATCH v12 10/33] KVM: Set the stage for handling only shared mappings in mmu_notifier events
From: Binbin Wu <hidden>
Date: 2023-09-18 01:15:14
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-fsdevel, linux-mips, linux-mm, linux-riscv, linuxppc-dev, lkml
On 9/14/2023 9:55 AM, Sean Christopherson wrote:
Add flags to "struct kvm_gfn_range" to let notifier events target only shared and only private mappings, and write up the existing mmu_notifier events to be shared-only (private memory is never associated with a userspace virtual address, i.e. can't be reached via mmu_notifiers). Add two flags so that KVM can handle the three possibilities (shared, private, and shared+private) without needing something like a tri-state enum.
How to understand the word "stage" in short log?
quoted hunk ↗ jump to hunk
Link: https://lore.kernel.org/all/ZJX0hk+KpQP0KUyB@google.com (local) Signed-off-by: Sean Christopherson <seanjc@google.com> --- include/linux/kvm_host.h | 2 ++ virt/kvm/kvm_main.c | 7 +++++++ 2 files changed, 9 insertions(+)diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index d8c6ce6c8211..b5373cee2b08 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h@@ -263,6 +263,8 @@ struct kvm_gfn_range { gfn_t start; gfn_t end; union kvm_mmu_notifier_arg arg; + bool only_private; + bool only_shared; bool may_block; }; bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 174de2789657..a41f8658dfe0 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c@@ -635,6 +635,13 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, * the second or later invocation of the handler). */ gfn_range.arg = range->arg; + + /* + * HVA-based notifications aren't relevant to private + * mappings as they don't have a userspace mapping. + */ + gfn_range.only_private = false; + gfn_range.only_shared = true; gfn_range.may_block = range->may_block; /*