File xsa435-0-03.patch of Package xen.31135

From b672695e748869b2e2e2cb03f671f12003d2b079 Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Fri, 11 Jun 2021 11:37:53 +0100
Subject: x86/msr: Expose MSR_ARCH_CAPS in the raw and host policies

MSR_ARCH_CAPS is still not supported for guests yet (other than the hardware
domain), until the toolstack learns how to construct an MSR policy.

However, we want access to the host ARCH_CAPS_TSX_CTRL value in particular for
testing purposes.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -40,8 +40,13 @@ struct vcpu_msrs __read_mostly hvm_max_v
 
 static void __init calculate_raw_policy(void)
 {
+    struct msr_policy *mp = &raw_msr_policy;
+
     /* 0x000000ce  MSR_INTEL_PLATFORM_INFO */
     /* Was already added by probe_cpuid_faulting() */
+
+    if ( cpu_has_arch_caps )
+        rdmsrl(MSR_ARCH_CAPABILITIES, mp->arch_caps.raw);
 }
 
 static void __init calculate_host_policy(void)
@@ -53,6 +58,12 @@ static void __init calculate_host_policy
     /* 0x000000ce  MSR_INTEL_PLATFORM_INFO */
     /* probe_cpuid_faulting() sanity checks presence of MISC_FEATURES_ENABLES */
     mp->platform_info.cpuid_faulting = cpu_has_cpuid_faulting;
+
+    /* Temporary, until we have known_features[] for feature bits in MSRs. */
+    mp->arch_caps.raw &=
+        (ARCH_CAPS_RDCL_NO | ARCH_CAPS_IBRS_ALL | ARCH_CAPS_RSBA |
+         ARCH_CAPS_SKIP_L1DFL | ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO |
+         ARCH_CAPS_IF_PSCHANGE_MC_NO | ARCH_CAPS_TSX_CTRL | ARCH_CAPS_TAA_NO);
 }
 
 static void __init calculate_hvm_max_policy(void)
@@ -66,6 +77,8 @@ static void __init calculate_hvm_max_pol
 
     /* It's always possible to emulate CPUID faulting for HVM guests */
     mp->platform_info.cpuid_faulting = true;
+
+    mp->arch_caps.raw = 0; /* Not supported yet. */
 }
 
 static void __init calculate_pv_max_policy(void)
@@ -73,6 +86,8 @@ static void __init calculate_pv_max_poli
     struct msr_policy *mp = &pv_max_msr_policy;
 
     *mp = host_msr_policy;
+
+    mp->arch_caps.raw = 0; /* Not supported yet. */
 }
 
 void __init init_guest_msr_policy(void)
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -133,6 +133,7 @@
 #define cpu_has_avx512_4vnniw   boot_cpu_has(X86_FEATURE_AVX512_4VNNIW)
 #define cpu_has_avx512_4fmaps   boot_cpu_has(X86_FEATURE_AVX512_4FMAPS)
 #define cpu_has_tsx_force_abort boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT)
+#define cpu_has_arch_caps       boot_cpu_has(X86_FEATURE_ARCH_CAPS)
 
 /* Synthesized. */
 #define cpu_has_arch_perfmon    boot_cpu_has(X86_FEATURE_ARCH_PERFMON)