On Thu, 5 Jun 2025 at 18:45, David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 05.06.25 19:43, Fuad Tabba wrote: > > 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... > > So, you mean a sofware VM is ... just an ordinary VM? :P > > "KVM: x86: Enable guest_memfd shared memory for ordinary (non-CoCo) VMs" ? > > But, whatever you prefer :) This sounds better. I was thrown off by the KVM_SW_PROTECTED_VM type :) /fuad > -- > Cheers, > > David / dhildenb >
