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Mon, 06 Nov 2023 03:01:09 -0800 (PST) MIME-Version: 1.0 References: <20231027182217.3615211-1-seanjc@google.com> <20231027182217.3615211-24-seanjc@google.com> In-Reply-To: <20231027182217.3615211-24-seanjc@google.com> From: Fuad Tabba Date: Mon, 6 Nov 2023 11:00:33 +0000 Message-ID: Subject: Re: [PATCH v13 23/35] KVM: x86: Add support for "protected VMs" that can utilize private memory To: Sean Christopherson Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , =?UTF-8?B?TWlja2HDq2wgU2FsYcO8bg==?= , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: AAFDD1C0020 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: fr5ftnst3t8s1nhgwcmtw8c8oc1ce5ej X-HE-Tag: 1699268470-14956 X-HE-Meta: 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 xSlsPedC 0gdXsoC88UO1yNN9jtT9KvT1NdB5a8qVMjhlyujT4eZ25ZOh9320Scnd9SK0cu+aX/AYqWsrLiHaW/ZQOMf/3wAliSrXN+g4sS6QHv32bH4v3qlabf72WdvJ0vkD9jgFO3EuJ1p6eJ/5RLohizlu/2RGIGXASMv7LesW+t75dxUbHwzd/UIxmFWk2Vo+XIjo7YUw4MjbuMXwsRxsftSM5SVJKTOqi3CyKn0XZrz+Fwt8yfotuB5kkt2dHsgWxwVr7670T3vHeI4NOSzEuNqQlmqNKpFj2mflSARu7qsiDR1aS7Qh2V1cy6SMhMD0tdhY1YbX+ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, On Fri, Oct 27, 2023 at 7:23=E2=80=AFPM Sean Christopherson wrote: > > Add a new x86 VM type, KVM_X86_SW_PROTECTED_VM, to serve as a development > and testing vehicle for Confidential (CoCo) VMs, and potentially to even > become a "real" product in the distant future, e.g. a la pKVM. > > The private memory support in KVM x86 is aimed at AMD's SEV-SNP and > Intel's TDX, but those technologies are extremely complex (understatement= ), > difficult to debug, don't support running as nested guests, and require > hardware that's isn't universally accessible. I.e. relying SEV-SNP or TD= X nit: "that isn't" Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Cheers, /fuad > for maintaining guest private memory isn't a realistic option. > > At the very least, KVM_X86_SW_PROTECTED_VM will enable a variety of > selftests for guest_memfd and private memory support without requiring > unique hardware. > > Signed-off-by: Sean Christopherson > --- > Documentation/virt/kvm/api.rst | 32 ++++++++++++++++++++++++++++++++ > arch/x86/include/asm/kvm_host.h | 15 +++++++++------ > arch/x86/include/uapi/asm/kvm.h | 3 +++ > arch/x86/kvm/Kconfig | 12 ++++++++++++ > arch/x86/kvm/mmu/mmu_internal.h | 1 + > arch/x86/kvm/x86.c | 16 +++++++++++++++- > include/uapi/linux/kvm.h | 1 + > virt/kvm/Kconfig | 5 +++++ > 8 files changed, 78 insertions(+), 7 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.= rst > index 38dc1fda4f45..00029436ac5b 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -147,10 +147,29 @@ described as 'basic' will be available. > The new VM has no virtual cpus and no memory. > You probably want to use 0 as machine type. > > +X86: > +^^^^ > + > +Supported X86 VM types can be queried via KVM_CAP_VM_TYPES. > + > +S390: > +^^^^^ > + > In order to create user controlled virtual machines on S390, check > KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as > privileged user (CAP_SYS_ADMIN). > > +MIPS: > +^^^^^ > + > +To use hardware assisted virtualization on MIPS (VZ ASE) rather than > +the default trap & emulate implementation (which changes the virtual > +memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the > +flag KVM_VM_MIPS_VZ. > + > +ARM64: > +^^^^^^ > + > On arm64, the physical address size for a VM (IPA Size limit) is limited > to 40bits by default. The limit can be configured if the host supports t= he > extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use > @@ -8650,6 +8669,19 @@ block sizes is exposed in KVM_CAP_ARM_SUPPORTED_BL= OCK_SIZES as a > 64-bit bitmap (each bit describing a block size). The default value is > 0, to disable the eager page splitting. > > +8.41 KVM_CAP_VM_TYPES > +--------------------- > + > +:Capability: KVM_CAP_MEMORY_ATTRIBUTES > +:Architectures: x86 > +:Type: system ioctl > + > +This capability returns a bitmap of support VM types. The 1-setting of = bit @n > +means the VM type with value @n is supported. Possible values of @n are= :: > + > + #define KVM_X86_DEFAULT_VM 0 > + #define KVM_X86_SW_PROTECTED_VM 1 > + > 9. Known KVM API problems > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_h= ost.h > index f9e8d5642069..dff10051e9b6 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1244,6 +1244,7 @@ enum kvm_apicv_inhibit { > }; > > struct kvm_arch { > + unsigned long vm_type; > unsigned long n_used_mmu_pages; > unsigned long n_requested_mmu_pages; > unsigned long n_max_mmu_pages; > @@ -2077,6 +2078,12 @@ void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t = new_pgd); > void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, > int tdp_max_root_level, int tdp_huge_page_level); > > +#ifdef CONFIG_KVM_PRIVATE_MEM > +#define kvm_arch_has_private_mem(kvm) ((kvm)->arch.vm_type !=3D KVM_X86_= DEFAULT_VM) > +#else > +#define kvm_arch_has_private_mem(kvm) false > +#endif > + > static inline u16 kvm_read_ldt(void) > { > u16 ldt; > @@ -2125,14 +2132,10 @@ enum { > #define HF_SMM_INSIDE_NMI_MASK (1 << 2) > > # define KVM_MAX_NR_ADDRESS_SPACES 2 > +/* SMM is currently unsupported for guests with private memory. */ > +# define kvm_arch_nr_memslot_as_ids(kvm) (kvm_arch_has_private_mem(kvm) = ? 1 : 2) > # define kvm_arch_vcpu_memslots_id(vcpu) ((vcpu)->arch.hflags & HF_SMM_M= ASK ? 1 : 0) > # define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, (role= ).smm) > - > -static inline int kvm_arch_nr_memslot_as_ids(struct kvm *kvm) > -{ > - return KVM_MAX_NR_ADDRESS_SPACES; > -} > - > #else > # define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, 0) > #endif > diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/= kvm.h > index 1a6a1f987949..a448d0964fc0 100644 > --- a/arch/x86/include/uapi/asm/kvm.h > +++ b/arch/x86/include/uapi/asm/kvm.h > @@ -562,4 +562,7 @@ struct kvm_pmu_event_filter { > /* x86-specific KVM_EXIT_HYPERCALL flags. */ > #define KVM_EXIT_HYPERCALL_LONG_MODE BIT(0) > > +#define KVM_X86_DEFAULT_VM 0 > +#define KVM_X86_SW_PROTECTED_VM 1 > + > #endif /* _ASM_X86_KVM_H */ > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index 091b74599c22..8452ed0228cb 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -77,6 +77,18 @@ config KVM_WERROR > > If in doubt, say "N". > > +config KVM_SW_PROTECTED_VM > + bool "Enable support for KVM software-protected VMs" > + depends on EXPERT > + depends on X86_64 > + select KVM_GENERIC_PRIVATE_MEM > + help > + Enable support for KVM software-protected VMs. Currently "prot= ected" > + means the VM can be backed with memory provided by > + KVM_CREATE_GUEST_MEMFD. > + > + If unsure, say "N". > + > config KVM_INTEL > tristate "KVM for Intel (and compatible) processors support" > depends on KVM && IA32_FEAT_CTL > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_inter= nal.h > index 86c7cb692786..b66a7d47e0e4 100644 > --- a/arch/x86/kvm/mmu/mmu_internal.h > +++ b/arch/x86/kvm/mmu/mmu_internal.h > @@ -297,6 +297,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vc= pu *vcpu, gpa_t cr2_or_gpa, > .max_level =3D KVM_MAX_HUGEPAGE_LEVEL, > .req_level =3D PG_LEVEL_4K, > .goal_level =3D PG_LEVEL_4K, > + .is_private =3D kvm_mem_is_private(vcpu->kvm, cr2_or_gpa = >> PAGE_SHIFT), > }; > int r; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index c4d17727b199..e3eb608b6692 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4441,6 +4441,13 @@ static int kvm_ioctl_get_supported_hv_cpuid(struct= kvm_vcpu *vcpu, > return 0; > } > > +static bool kvm_is_vm_type_supported(unsigned long type) > +{ > + return type =3D=3D KVM_X86_DEFAULT_VM || > + (type =3D=3D KVM_X86_SW_PROTECTED_VM && > + IS_ENABLED(CONFIG_KVM_SW_PROTECTED_VM) && tdp_enabled); > +} > + > int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > { > int r =3D 0; > @@ -4632,6 +4639,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, = long ext) > case KVM_CAP_X86_NOTIFY_VMEXIT: > r =3D kvm_caps.has_notify_vmexit; > break; > + case KVM_CAP_VM_TYPES: > + r =3D BIT(KVM_X86_DEFAULT_VM); > + if (kvm_is_vm_type_supported(KVM_X86_SW_PROTECTED_VM)) > + r |=3D BIT(KVM_X86_SW_PROTECTED_VM); > + break; > default: > break; > } > @@ -12314,9 +12326,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned l= ong type) > int ret; > unsigned long flags; > > - if (type) > + if (!kvm_is_vm_type_supported(type)) > return -EINVAL; > > + kvm->arch.vm_type =3D type; > + > ret =3D kvm_page_track_init(kvm); > if (ret) > goto out; > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 29e9eb51dec9..5b5820d19e71 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1218,6 +1218,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_MEMORY_FAULT_INFO 231 > #define KVM_CAP_MEMORY_ATTRIBUTES 232 > #define KVM_CAP_GUEST_MEMFD 233 > +#define KVM_CAP_VM_TYPES 234 > > #ifdef KVM_CAP_IRQ_ROUTING > > diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig > index 08afef022db9..2c964586aa14 100644 > --- a/virt/kvm/Kconfig > +++ b/virt/kvm/Kconfig > @@ -104,3 +104,8 @@ config KVM_GENERIC_MEMORY_ATTRIBUTES > config KVM_PRIVATE_MEM > select XARRAY_MULTI > bool > + > +config KVM_GENERIC_PRIVATE_MEM > + select KVM_GENERIC_MEMORY_ATTRIBUTES > + select KVM_PRIVATE_MEM > + bool > -- > 2.42.0.820.g83a721a137-goog >