On Thu, 5 Jun 2025 at 18:35, David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 05.06.25 18:11, Fuad Tabba wrote: > > On Thu, 5 Jun 2025 at 16:49, David Hildenbrand <david@xxxxxxxxxx> wrote: > >> > >> On 05.06.25 17:37, Fuad Tabba wrote: > >>> Define the architecture-specific macro to enable shared memory support > >>> in guest_memfd for relevant software-only VM types, specifically > >>> KVM_X86_DEFAULT_VM and KVM_X86_SW_PROTECTED_VM. > >>> > >>> Enable the KVM_GMEM_SHARED_MEM Kconfig option if KVM_SW_PROTECTED_VM is > >>> enabled. > >>> > >>> Co-developed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx> > >>> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx> > >>> Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx> > >>> --- > >>> arch/x86/include/asm/kvm_host.h | 10 ++++++++++ > >>> arch/x86/kvm/Kconfig | 1 + > >>> arch/x86/kvm/x86.c | 3 ++- > >>> 3 files changed, 13 insertions(+), 1 deletion(-) > >>> > >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > >>> index 709cc2a7ba66..ce9ad4cd93c5 100644 > >>> --- a/arch/x86/include/asm/kvm_host.h > >>> +++ b/arch/x86/include/asm/kvm_host.h > >>> @@ -2255,8 +2255,18 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, > >>> > >>> #ifdef CONFIG_KVM_GMEM > >>> #define kvm_arch_supports_gmem(kvm) ((kvm)->arch.supports_gmem) > >>> + > >>> +/* > >>> + * CoCo VMs with hardware support that use guest_memfd only for backing private > >>> + * memory, e.g., TDX, cannot use guest_memfd with userspace mapping enabled. > >>> + */ > >>> +#define kvm_arch_supports_gmem_shared_mem(kvm) \ > >>> + (IS_ENABLED(CONFIG_KVM_GMEM_SHARED_MEM) && \ > >>> + ((kvm)->arch.vm_type == KVM_X86_SW_PROTECTED_VM || \ > >>> + (kvm)->arch.vm_type == KVM_X86_DEFAULT_VM)) > >>> #else > >>> #define kvm_arch_supports_gmem(kvm) false > >>> +#define kvm_arch_supports_gmem_shared_mem(kvm) false > >>> #endif > >>> > >>> #define kvm_arch_has_readonly_mem(kvm) (!(kvm)->arch.has_protected_state) > >>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > >>> index b37258253543..fdf24b50af9d 100644 > >>> --- a/arch/x86/kvm/Kconfig > >>> +++ b/arch/x86/kvm/Kconfig > >>> @@ -47,6 +47,7 @@ config KVM_X86 > >>> select KVM_GENERIC_HARDWARE_ENABLING > >>> select KVM_GENERIC_PRE_FAULT_MEMORY > >>> select KVM_GENERIC_GMEM_POPULATE if KVM_SW_PROTECTED_VM > >>> + select KVM_GMEM_SHARED_MEM if KVM_SW_PROTECTED_VM > >>> select KVM_WERROR if WERROR > >> > >> Is $subject and this still true, given that it's now also supported for > >> KVM_X86_DEFAULT_VM? > > > > True, just not the whole truth :) > > > > I guess a better one would be, for Software VMs (remove protected)? > > Now I am curious, what is a Hardware VM? :) The opposite of a software one! ;) i.e., hardware-supported CoCo, e.g., TDX, CCA... Cheers, /fuad > -- > Cheers, > > David / dhildenb >
