queue-4.4/kvm-x86-report-stibp-on-get_supported_cpuid.patch

   1 From foo@baz Tue 14 May 2019 08:29:35 PM CEST
   2 From: Eduardo Habkost <ehabkost@redhat.com>
   3 Date: Wed, 5 Dec 2018 17:19:56 -0200
   4 Subject: kvm: x86: Report STIBP on GET_SUPPORTED_CPUID
   5
   6 From: Eduardo Habkost <ehabkost@redhat.com>
   7
   8 commit d7b09c827a6cf291f66637a36f46928dd1423184 upstream.
   9
  10 Months ago, we have added code to allow direct access to MSR_IA32_SPEC_CTRL
  11 to the guest, which makes STIBP available to guests.  This was implemented
  12 by commits d28b387fb74d ("KVM/VMX: Allow direct access to
  13 MSR_IA32_SPEC_CTRL") and b2ac58f90540 ("KVM/SVM: Allow direct access to
  14 MSR_IA32_SPEC_CTRL").
  15
  16 However, we never updated GET_SUPPORTED_CPUID to let userspace know that
  17 STIBP can be enabled in CPUID.  Fix that by updating
  18 kvm_cpuid_8000_0008_ebx_x86_features and kvm_cpuid_7_0_edx_x86_features.
  19
  20 Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
  21 Reviewed-by: Jim Mattson <jmattson@google.com>
  22 Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
  23 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  24 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  25 [bwh: Backported to 4.4: adjust context]
  26 Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28 ---
  29  arch/x86/kvm/cpuid.c |    5 +++--
  30  1 file changed, 3 insertions(+), 2 deletions(-)
  31
  32 --- a/arch/x86/kvm/cpuid.c
  33 +++ b/arch/x86/kvm/cpuid.c
  34 @@ -344,7 +344,7 @@ static inline int __do_cpuid_ent(struct
  35         /* cpuid 0x80000008.ebx */
  36         const u32 kvm_cpuid_8000_0008_ebx_x86_features =
  37                 F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
  38 -               F(AMD_SSB_NO);
  39 +               F(AMD_SSB_NO) | F(AMD_STIBP);
  40
  41         /* cpuid 0xC0000001.edx */
  42         const u32 kvm_supported_word5_x86_features =
  43 @@ -365,7 +365,8 @@ static inline int __do_cpuid_ent(struct
  44
  45         /* cpuid 7.0.edx*/
  46         const u32 kvm_cpuid_7_0_edx_x86_features =
  47 -               F(SPEC_CTRL) | F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES);
  48 +               F(SPEC_CTRL) | F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) |
  49 +               F(INTEL_STIBP);
  50
  51         /* all calls to cpuid_count() should be made on the same cpu */
  52         get_cpu();