On Tue, Mar 04, 2025 at 09:27:06AM +0000, Fuad Tabba wrote: > Hi Kirill, > > On Tue, 4 Mar 2025 at 08:58, Kirill A. Shutemov > <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > > > > On Mon, Mar 03, 2025 at 05:10:07PM +0000, Fuad Tabba wrote: > > > Add support for mmap() and fault() for guest_memfd backed memory > > > in the host for VMs that support in-place conversion between > > > shared and private. To that end, this patch adds the ability to > > > check whether the VM type supports in-place conversion, and only > > > allows mapping its memory if that's the case. > > > > > > Also add the KVM capability KVM_CAP_GMEM_SHARED_MEM, which > > > indicates that the VM supports shared memory in guest_memfd, or > > > that the host can create VMs that support shared memory. > > > Supporting shared memory implies that memory can be mapped when > > > shared with the host. > > > > > > This is controlled by the KVM_GMEM_SHARED_MEM configuration > > > option. > > > > > > Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx> > > > --- > > > include/linux/kvm_host.h | 11 ++++ > > > include/uapi/linux/kvm.h | 1 + > > > virt/kvm/guest_memfd.c | 105 +++++++++++++++++++++++++++++++++++++++ > > > virt/kvm/kvm_main.c | 4 ++ > > > 4 files changed, 121 insertions(+) > > > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > > index 7788e3625f6d..2d025b8ee20e 100644 > > > --- a/include/linux/kvm_host.h > > > +++ b/include/linux/kvm_host.h > > > @@ -728,6 +728,17 @@ static inline bool kvm_arch_has_private_mem(struct kvm *kvm) > > > } > > > #endif > > > > > > +/* > > > + * Arch code must define kvm_arch_gmem_supports_shared_mem if support for > > > + * private memory is enabled and it supports in-place shared/private conversion. > > > + */ > > > +#if !defined(kvm_arch_gmem_supports_shared_mem) && !IS_ENABLED(CONFIG_KVM_PRIVATE_MEM) > > > > Hm. Do we expect any caller for !CONFIG_KVM_PRIVATE_MEM? I think you missed this. -- Kiryl Shutsemau / Kirill A. Shutemov
