| Message ID | 20231027182217.3615211-24-seanjc@google.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | KVM: guest_memfd() and per-page attributes | expand |
On 10/27/23 20:22, 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 TDX > 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 <seanjc@google.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> with one nit: > +--------------------- > + > +: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 s/support/supported/ Paolo
Hi, On Fri, Oct 27, 2023 at 7:23 PM Sean Christopherson <seanjc@google.com> 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 TDX nit: "that isn't" Reviewed-by: Fuad Tabba <tabba@google.com> Tested-by: Fuad Tabba <tabba@google.com> 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 <seanjc@google.com> > --- > 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 the > extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use > @@ -8650,6 +8669,19 @@ block sizes is exposed in KVM_CAP_ARM_SUPPORTED_BLOCK_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 > ========================= > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.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 != 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_MASK ? 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 "protected" > + 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_internal.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_vcpu *vcpu, gpa_t cr2_or_gpa, > .max_level = KVM_MAX_HUGEPAGE_LEVEL, > .req_level = PG_LEVEL_4K, > .goal_level = PG_LEVEL_4K, > + .is_private = 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 == KVM_X86_DEFAULT_VM || > + (type == 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 = 0; > @@ -4632,6 +4639,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_X86_NOTIFY_VMEXIT: > r = kvm_caps.has_notify_vmexit; > break; > + case KVM_CAP_VM_TYPES: > + r = BIT(KVM_X86_DEFAULT_VM); > + if (kvm_is_vm_type_supported(KVM_X86_SW_PROTECTED_VM)) > + r |= BIT(KVM_X86_SW_PROTECTED_VM); > + break; > default: > break; > } > @@ -12314,9 +12326,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > int ret; > unsigned long flags; > > - if (type) > + if (!kvm_is_vm_type_supported(type)) > return -EINVAL; > > + kvm->arch.vm_type = type; > + > ret = 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 >
On 11/6/23 12:00, Fuad Tabba wrote: > Hi, > > > On Fri, Oct 27, 2023 at 7:23 PM Sean Christopherson <seanjc@google.com> 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 TDX > > nit: "that isn't" > > Reviewed-by: Fuad Tabba <tabba@google.com> > Tested-by: Fuad Tabba <tabba@google.com> Hi Fuad, thanks for your reviews and tests of the gmem patches! Can you please continue replying to v14? Thanks, Paolo > 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 <seanjc@google.com> >> --- >> 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 the >> extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use >> @@ -8650,6 +8669,19 @@ block sizes is exposed in KVM_CAP_ARM_SUPPORTED_BLOCK_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 >> ========================= >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.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 != 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_MASK ? 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 "protected" >> + 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_internal.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_vcpu *vcpu, gpa_t cr2_or_gpa, >> .max_level = KVM_MAX_HUGEPAGE_LEVEL, >> .req_level = PG_LEVEL_4K, >> .goal_level = PG_LEVEL_4K, >> + .is_private = 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 == KVM_X86_DEFAULT_VM || >> + (type == 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 = 0; >> @@ -4632,6 +4639,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) >> case KVM_CAP_X86_NOTIFY_VMEXIT: >> r = kvm_caps.has_notify_vmexit; >> break; >> + case KVM_CAP_VM_TYPES: >> + r = BIT(KVM_X86_DEFAULT_VM); >> + if (kvm_is_vm_type_supported(KVM_X86_SW_PROTECTED_VM)) >> + r |= BIT(KVM_X86_SW_PROTECTED_VM); >> + break; >> default: >> break; >> } >> @@ -12314,9 +12326,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) >> int ret; >> unsigned long flags; >> >> - if (type) >> + if (!kvm_is_vm_type_supported(type)) >> return -EINVAL; >> >> + kvm->arch.vm_type = type; >> + >> ret = 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 >> >
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 the extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use @@ -8650,6 +8669,19 @@ block sizes is exposed in KVM_CAP_ARM_SUPPORTED_BLOCK_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 ========================= diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.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 != 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_MASK ? 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 "protected" + 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_internal.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_vcpu *vcpu, gpa_t cr2_or_gpa, .max_level = KVM_MAX_HUGEPAGE_LEVEL, .req_level = PG_LEVEL_4K, .goal_level = PG_LEVEL_4K, + .is_private = 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 == KVM_X86_DEFAULT_VM || + (type == 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 = 0; @@ -4632,6 +4639,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_X86_NOTIFY_VMEXIT: r = kvm_caps.has_notify_vmexit; break; + case KVM_CAP_VM_TYPES: + r = BIT(KVM_X86_DEFAULT_VM); + if (kvm_is_vm_type_supported(KVM_X86_SW_PROTECTED_VM)) + r |= BIT(KVM_X86_SW_PROTECTED_VM); + break; default: break; } @@ -12314,9 +12326,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) int ret; unsigned long flags; - if (type) + if (!kvm_is_vm_type_supported(type)) return -EINVAL; + kvm->arch.vm_type = type; + ret = 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
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 TDX 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 <seanjc@google.com> --- 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(-)