• Tom Lendacky's avatar
    KVM: x86: Assume a 64-bit hypercall for guests with protected state · b5aead00
    Tom Lendacky authored
    When processing a hypercall for a guest with protected state, currently
    SEV-ES guests, the guest CS segment register can't be checked to
    determine if the guest is in 64-bit mode. For an SEV-ES guest, it is
    expected that communication between the guest and the hypervisor is
    performed to shared memory using the GHCB. In order to use the GHCB, the
    guest must have been in long mode, otherwise writes by the guest to the
    GHCB would be encrypted and not be able to be comprehended by the
    hypervisor.
    
    Create a new helper function, is_64_bit_hypercall(), that assumes the
    guest is in 64-bit mode when the guest has protected state, and returns
    true, otherwise invoking is_64_bit_mode() to determine the mode. Update
    the hypercall related routines to use is_64_bit_hypercall() instead of
    is_64_bit_mode().
    
    Add a WARN_ON_ONCE() to is_64_bit_mode() to catch occurences of calls to
    this helper function for a guest running with protected state.
    
    Fixes: f1c6366e ("KVM: SVM: Add required changes to support intercepts under SEV-ES")
    Reported-by: default avatarSean Christopherson <seanjc@google.com>
    Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
    Message-Id: <e0b20c770c9d0d1403f23d83e785385104211f74.1621878537.git.thomas.lendacky@amd.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    b5aead00
hyperv.c 65.9 KB