linux-kernel - [PATCH v2 0/3] KVM: x86: SGX vs. XCR0 cleanups

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Date:   Wed,  3 May 2023 09:08:35 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kai Huang <kai.huang@...el.com>
Subject: [PATCH v2 0/3] KVM: x86: SGX vs. XCR0 cleanups

Stop adjusting the guest's CPUID info for the allowed XFRM (a.k.a. XCR0)
for SGX enclaves.  Past me didn't understand the roles and responsibilities
between userspace and KVM with respect to CPUID leafs, i.e. I thought I was
being helpful by having KVM adjust the entries.

This is clearly an ABI change, but QEMU does the right thing and AFAIK no
other VMMs support SGX (yet), so I'm hopeful/confident that we can excise
the ugly before userspace starts depending on the bad behavior.

v2:
 - Collect reviews/testing. [Kai]
 - Require FP+SSE to always be set in XFRM, and exempt them from the XFRM
   vs. XCR0 check. [Kai]

v1: https://lore.kernel.org/all/20230405005911.423699-1-seanjc@google.com

Sean Christopherson (3):
  KVM: VMX: Don't rely _only_ on CPUID to enforce XCR0 restrictions for
    ECREATE
  KVM: x86: Don't adjust guest's CPUID.0x12.1 (allowed SGX enclave XFRM)
  KVM: x86: Open code supported XCR0 calculation in
    kvm_vcpu_after_set_cpuid()

 arch/x86/kvm/cpuid.c   | 43 ++++++++++--------------------------------
 arch/x86/kvm/vmx/sgx.c | 11 +++++++++--
 2 files changed, 19 insertions(+), 35 deletions(-)

base-commit: 5c291b93e5d665380dbecc6944973583f9565ee5
-- 
2.40.1.495.gc816e09b53d-goog