From 89ea60c2c7b5838bf192c50062d5720cd6ab8662 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 27 Oct 2023 11:22:05 -0700 Subject: KVM: x86: Add support for "protected VMs" that can utilize private memory 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 Reviewed-by: Paolo Bonzini Message-Id: <20231027182217.3615211-24-seanjc@google.com> Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Signed-off-by: Paolo Bonzini --- Documentation/virt/kvm/api.rst | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'Documentation/virt') diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 726c87c35d57..926241e23aeb 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 @@ -8765,6 +8784,19 @@ 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 ========================= -- cgit