[xen stable-4.17] x86/spec-ctrl: Expose BHI_CTRL to guests

[patchbot@xxxxxxx]

commit 363745e52dc758bdfb2fd42d32f12276c80ed447
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Tue Jan 30 10:14:00 2024 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Apr 9 16:48:19 2024 +0100

    x86/spec-ctrl: Expose BHI_CTRL to guests
    
    The CPUID feature bit signals the presence of the BHI_DIS_S control in
    SPEC_CTRL MSR, first available in Intel AlderLake and Sapphire Rapids CPUs
    
    Xen already knows how to context switch MSR_SPEC_CTRL properly between guest
    and hypervisor context.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    (cherry picked from commit 583f1d0950529f3517b1741c2b21a028a82ba831)
---
 xen/arch/x86/msr.c                          | 1 +
 xen/include/public/arch-x86/cpufeatureset.h | 2 +-
 xen/tools/gen-cpuid.py                      | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index 615314f1e1..51e6744e8f 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -335,6 +335,7 @@ uint64_t msr_spec_ctrl_valid_bits(const struct cpu_policy 
*cp)
              ? (SPEC_CTRL_IPRED_DIS_U | SPEC_CTRL_IPRED_DIS_S) : 0) |
             (cp->feat.rrsba_ctrl
              ? (SPEC_CTRL_RRSBA_DIS_U | SPEC_CTRL_RRSBA_DIS_S) : 0) |
+            (cp->feat.bhi_ctrl   ? SPEC_CTRL_BHI_DIS_S : 0) |
             0);
 }
 
diff --git a/xen/include/public/arch-x86/cpufeatureset.h 
b/xen/include/public/arch-x86/cpufeatureset.h
index 0e1581cdac..51f238683c 100644
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -297,7 +297,7 @@ XEN_CPUFEATURE(INTEL_PPIN,         12*32+ 0) /*   Protected 
Processor Inventory
 XEN_CPUFEATURE(INTEL_PSFD,         13*32+ 0) /*A  MSR_SPEC_CTRL.PSFD */
 XEN_CPUFEATURE(IPRED_CTRL,         13*32+ 1) /*A  MSR_SPEC_CTRL.IPRED_DIS_* */
 XEN_CPUFEATURE(RRSBA_CTRL,         13*32+ 2) /*A  MSR_SPEC_CTRL.RRSBA_DIS_* */
-XEN_CPUFEATURE(BHI_CTRL,           13*32+ 4) /*   MSR_SPEC_CTRL.BHI_DIS_S */
+XEN_CPUFEATURE(BHI_CTRL,           13*32+ 4) /*A  MSR_SPEC_CTRL.BHI_DIS_S */
 XEN_CPUFEATURE(MCDT_NO,            13*32+ 5) /*A  MCDT_NO */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:1.ecx, word 14 */
diff --git a/xen/tools/gen-cpuid.py b/xen/tools/gen-cpuid.py
index 09acb9764c..a7c2ba3e5d 100755
--- a/xen/tools/gen-cpuid.py
+++ b/xen/tools/gen-cpuid.py
@@ -319,7 +319,7 @@ def crunch_numbers(state):
         # as dependent features simplifies Xen's logic, and prevents the guest
         # from seeing implausible configurations.
         IBRSB: [STIBP, SSBD, INTEL_PSFD, EIBRS,
-                IPRED_CTRL, RRSBA_CTRL],
+                IPRED_CTRL, RRSBA_CTRL, BHI_CTRL],
         IBRS: [AMD_STIBP, AMD_SSBD, PSFD,
                IBRS_ALWAYS, IBRS_FAST, IBRS_SAME_MODE],
         IBPB: [IBPB_RET, SBPB, IBPB_BRTYPE],
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.17