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SubjectRe: [PATCH v1 0/6] LASS KVM virtualization support
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On 6/5/2023 9:39 AM, Binbin Wu wrote:
>
> On 6/1/2023 10:23 PM, Zeng Guang wrote:
>> Subject:
>> [PATCH v1 0/6] LASS KVM virtualization support
>> From:
>> Zeng Guang <guang.zeng@intel.com>
>> Date:
>> 6/1/2023, 10:23 PM
>>
>> To:
>> Paolo Bonzini <pbonzini@redhat.com>, Sean Christopherson
>> <seanjc@google.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar
>> <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Dave Hansen
>> <dave.hansen@linux.intel.com>, H Peter Anvin <hpa@zytor.com>,
>> kvm@vger.kernel.org
>> CC:
>> x86@kernel.org, linux-kernel@vger.kernel.org, Zeng Guang
>> <guang.zeng@intel.com>
>>
>>
>> Linear Address Space Separation (LASS)[1] is an independent mechanism
>> that enforces the mode-based protections on any access to a linear
>> address.
>>
>> Based on a linear-address organization, the 64-bit canonical linear
>> address space is partitioned into two halves: all linear addresses
>> whose most significant bit is 0 are user space addresses, while linear
>> addresses whose most significant bit is 1 are supervisor space address.
>>
>> LASS aims to prevent any attempt to probe supervisor space addresses by
>> user mode, and likewise stop any attempt to access (if SMAP enabled) or
>> execute user space addresses from supervisor mode.
>>
>> When platform has LASS capability, KVM requires to expose this feature
>> to guest VM enumerated by CPUID.(EAX=07H.ECX=1):EAX.LASS[bit 6], and
>> allow guest to enable it via CR4.LASS[bit 27] on demand. For instruction
>> executed in the guest directly, hardware will perform the check. But KVM
>> also needs to behave same as hardware to apply LASS to kinds of guest
>> memory accesses when emulating privileged instructions by software.
> Not just privileged instructions, e.g. MMIO access instructions.
OK. I'll revise it.
>> KVM will take following LASS voilations check on emulation path.
> /s/voilations/violations
Thanks.
>> User-mode access to supervisor space address:
>> LA[bit 63] && (CPL == 3)
>> Supervisor-mode access to user space address:
>> Instruction fetch: !LA[bit 63] && (CPL < 3)
>> Data access: !LA[bit 63] && (CR4.SMAP==1) && ((RFLAGS.AC == 0 &&
>> CPL < 3) || Implicit supervisor access)
>>
>> This patch series provide a LASS KVM solution.
>>
>> We tested the basic function of LASS virtualization including LASS
>> enumeration and enabling in non-root and nested environment. As KVM
>> unittest framework is not compatible to LASS rule, we use kernel module
>> and application test to emulate LASS violation instead. With KVM forced
>> emulation mechanism, we also verified the LASS functionality on some
>> emulation path with instruction fetch and data access to have same
>> behavior as hardware.
>>
>> [1] Intel ISEhttps://cdrdv2.intel.com/v1/dl/getContent/671368
>> Chapter Linear Address Space Separation (LASS)
>>
>> ------------------------------------------------------
>>
>> v0->v1
>> 1. Adapt to new __linearize() API
>> 2. Function refactor of vmx_check_lass()
>> 3. Refine commit message to be more precise
>> 4. Drop LASS kvm cap detection depending
>> on hardware capability
>>
>>
>> Binbin Wu (1):
>> KVM: x86: Consolidate flags for __linearize()
>>
>> Zeng Guang (5):
>> KVM: x86: Virtualize CR4.LASS
>> KVM: VMX: Add new ops in kvm_x86_ops for LASS violation check
>> KVM: x86: Add emulator helper for LASS violation check
>> KVM: x86: LASS protection on KVM emulation
>> KVM: x86: Advertise LASS CPUID to user space
>>
>> arch/x86/include/asm/kvm-x86-ops.h | 3 +-
>> arch/x86/include/asm/kvm_host.h | 4 ++-
>> arch/x86/kvm/cpuid.c | 5 ++-
>> arch/x86/kvm/emulate.c | 47 +++++++++++++++++++++++-----
>> arch/x86/kvm/kvm_emulate.h | 6 ++++
>> arch/x86/kvm/vmx/nested.c | 3 ++
>> arch/x86/kvm/vmx/sgx.c | 4 +++
>> arch/x86/kvm/vmx/vmx.c | 50 ++++++++++++++++++++++++++++++
>> arch/x86/kvm/vmx/vmx.h | 2 ++
>> arch/x86/kvm/x86.c | 12 +++++++
>> arch/x86/kvm/x86.h | 2 ++
>> 11 files changed, 126 insertions(+), 12 deletions(-)
>>
>> -- 2.27.0

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