From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: x86/amd: Enumeration for speculative features/hints

There is a step change in speculation protections between the Zen1 and Zen2
microarchitectures.

Zen1 and older have no special support.  Control bits in non-architectural
MSRs are used to make lfence be dispatch-serialising (Spectre v1), and to
disable Memory Disambiguation (Speculative Store Bypass).  IBPB was
retrofitted in a microcode update, and software methods are required for
Spectre v2 protections.

Because the bit controlling Memory Disambiguation is model specific,
hypervisors are expected to expose a MSR_VIRT_SPEC_CTRL interface which
abstracts the model specific details.

Zen2 and later implement the MSR_SPEC_CTRL interface in hardware, and
virtualise the interface for HVM guests to use.  A number of hint bits are
specified too to help guide OS software to the most efficient mitigation
strategy.

Zen3 introduced a new feature, Predictive Store Forwarding, along with a
control to disable it in sensitive code.

Add CPUID and VMCB details for all the new functionality.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 747424c664bb164a04e7a9f2ffbf02d4a1630d7d)

--- a/tools/libxl/libxl_cpuid.c
+++ b/tools/libxl/libxl_cpuid.c
@@ -195,6 +195,16 @@ int libxl_cpuid_parse_config(libxl_cpuid
         {"syscall",      0x80000001, NA, CPUID_REG_EDX, 11,  1},
         {"procpkg",      0x00000004,  0, CPUID_REG_EAX, 26,  6},
         {"ibpb",         0x80000008, NA, CPUID_REG_EBX, 12,  1},
+        {"ibrs",         0x80000008, NA, CPUID_REG_EBX, 14,  1},
+        {"amd-stibp",    0x80000008, NA, CPUID_REG_EBX, 15,  1},
+        {"ibrs-always",  0x80000008, NA, CPUID_REG_EBX, 16,  1},
+        {"stibp-always", 0x80000008, NA, CPUID_REG_EBX, 17,  1},
+        {"ibrs-fast",    0x80000008, NA, CPUID_REG_EBX, 18,  1},
+        {"ibrs-same-mode", 0x80000008, NA, CPUID_REG_EBX, 19,  1},
+        {"amd-ssbd",     0x80000008, NA, CPUID_REG_EBX, 24,  1},
+        {"virt-ssbd",    0x80000008, NA, CPUID_REG_EBX, 25,  1},
+        {"ssb-no",       0x80000008, NA, CPUID_REG_EBX, 26,  1},
+        {"psfd",         0x80000008, NA, CPUID_REG_EBX, 28,  1},
         {"apicidsize",   0x80000008, NA, CPUID_REG_ECX, 12,  4},
         {"nc",           0x80000008, NA, CPUID_REG_ECX,  0,  8},
         {"svm_npt",      0x8000000a, NA, CPUID_REG_EDX,  0,  1},
--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -142,9 +142,18 @@ static const char *str_e8b[32] =
 
     [1 ... 11] = "REZ",
 
-    [12] = "ibpb",
+    [12] = "ibpb",             [13] = "REZ",
+    [14] = "ibrs",             [15] = "amd-stibp",
+    [16] = "ibrs-always",      [17] = "stibp-always",
+    [18] = "ibrs-fast",        [19] = "ibrs-same-mode",
 
-    [13 ... 31] = "REZ",
+    [20 ... 23] = "REZ",
+
+    [24] = "amd-ssbd",         [25] = "virt-ssbd",
+    [26] = "ssb-no",           [27] = "REZ",
+    [28] = "psfd",             [29] = "REZ",
+
+    [30 ... 31] = "REZ",
 };
 
 static const char *str_7d0[32] =
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1497,6 +1497,7 @@ const struct hvm_function_table * __init
     P(cpu_has_svm_decode, "DecodeAssists");
     P(cpu_has_pause_filter, "Pause-Intercept Filter");
     P(cpu_has_tsc_ratio, "TSC Rate MSR");
+    P(cpu_has_svm_spec_ctrl, "MSR_SPEC_CTRL virtualisation");
 #undef P
 
     if ( !printed )
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -119,6 +119,11 @@ XEN_CPUFEATURE(XEN_SELFSNOOP,   (FSCAPIN
 #define cpu_has_lfence_dispatch boot_cpu_has(X86_FEATURE_LFENCE_DISPATCH)
 #define cpu_has_no_xpti         boot_cpu_has(X86_FEATURE_NO_XPTI)
 
+/* CPUID level 0x80000008.ebx */
+#define cpu_has_amd_ssbd        boot_cpu_has(X86_FEATURE_AMD_SSBD)
+#define cpu_has_virt_ssbd       boot_cpu_has(X86_FEATURE_VIRT_SSBD)
+#define cpu_has_ssb_no          boot_cpu_has(X86_FEATURE_SSB_NO)
+
 enum _cache_type {
     CACHE_TYPE_NULL = 0,
     CACHE_TYPE_DATA = 1,
--- a/xen/include/asm-x86/hvm/svm/svm.h
+++ b/xen/include/asm-x86/hvm/svm/svm.h
@@ -81,6 +81,7 @@ extern u32 svm_feature_flags;
 #define SVM_FEATURE_FLUSHBYASID    6 /* TLB flush by ASID support */
 #define SVM_FEATURE_DECODEASSISTS  7 /* Decode assists support */
 #define SVM_FEATURE_PAUSEFILTER   10 /* Pause intercept filter support */
+#define SVM_FEATURE_SPEC_CTRL     20 /* MSR_SPEC_CTRL virtualisation */
 
 #define cpu_has_svm_feature(f) test_bit(f, &svm_feature_flags)
 #define cpu_has_svm_npt       cpu_has_svm_feature(SVM_FEATURE_NPT)
@@ -91,6 +92,7 @@ extern u32 svm_feature_flags;
 #define cpu_has_svm_decode    cpu_has_svm_feature(SVM_FEATURE_DECODEASSISTS)
 #define cpu_has_pause_filter  cpu_has_svm_feature(SVM_FEATURE_PAUSEFILTER)
 #define cpu_has_tsc_ratio     cpu_has_svm_feature(SVM_FEATURE_TSCRATEMSR)
+#define cpu_has_svm_spec_ctrl cpu_has_svm_feature(SVM_FEATURE_SPEC_CTRL)
 
 #define SVM_PAUSEFILTER_INIT    3000
 
--- a/xen/include/asm-x86/hvm/svm/vmcb.h
+++ b/xen/include/asm-x86/hvm/svm/vmcb.h
@@ -485,7 +485,9 @@ struct vmcb_struct {
     u64 _lastbranchtoip;        /* cleanbit 10 */
     u64 _lastintfromip;         /* cleanbit 10 */
     u64 _lastinttoip;           /* cleanbit 10 */
-    u64 res16[301];
+    u64 res16[9];
+    u64 spec_ctrl;
+    u64 res17[291];
 };
 
 struct svm_domain {
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -40,6 +40,7 @@
 #define SPEC_CTRL_IBRS			(_AC(1, ULL) << 0)
 #define SPEC_CTRL_STIBP			(_AC(1, ULL) << 1)
 #define SPEC_CTRL_SSBD			(_AC(1, ULL) << 2)
+#define SPEC_CTRL_PSFD			(_AC(1, ULL) << 7)
 
 #define MSR_PRED_CMD			0x00000049
 #define PRED_CMD_IBPB			(_AC(1, ULL) << 0)
@@ -257,6 +258,9 @@
 
 #define MSR_F15H_CU_POWER		0xc001007a
 #define MSR_F15H_CU_MAX_POWER		0xc001007b
+
+#define MSR_VIRT_SPEC_CTRL		0xc001011f /* Layout matches MSR_SPEC_CTRL */
+
 #define MSR_AMD_FAM15H_EVNTSEL0		0xc0010200
 #define MSR_AMD_FAM15H_PERFCTR0		0xc0010201
 #define MSR_AMD_FAM15H_EVNTSEL1		0xc0010202
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -226,6 +226,16 @@ XEN_CPUFEATURE(EFRO,          7*32+10) /
 /* AMD-defined CPU features, CPUID level 0x80000008.ebx, word 8 */
 XEN_CPUFEATURE(CLZERO,        8*32+ 0) /*A  CLZERO instruction */
 XEN_CPUFEATURE(IBPB,          8*32+12) /*A  IBPB support only (no IBRS, used by AMD) */
+XEN_CPUFEATURE(IBRS,          8*32+14) /*   MSR_SPEC_CTRL.IBRS */
+XEN_CPUFEATURE(AMD_STIBP,     8*32+15) /*   MSR_SPEC_CTRL.STIBP */
+XEN_CPUFEATURE(IBRS_ALWAYS,   8*32+16) /*   IBRS preferred always on */
+XEN_CPUFEATURE(STIBP_ALWAYS,  8*32+17) /*   STIBP preferred always on */
+XEN_CPUFEATURE(IBRS_FAST,     8*32+18) /*   IBRS preferred over software options */
+XEN_CPUFEATURE(IBRS_SAME_MODE, 8*32+19) /*   IBRS provides same-mode protection */
+XEN_CPUFEATURE(AMD_SSBD,      8*32+24) /*   MSR_SPEC_CTRL.SSBD available */
+XEN_CPUFEATURE(VIRT_SSBD,     8*32+25) /*   MSR_VIRT_SPEC_CTRL.SSBD */
+XEN_CPUFEATURE(SSB_NO,        8*32+26) /*   Hardware not vulnerable to SSB */
+XEN_CPUFEATURE(PSFD,          8*32+28) /*   MSR_SPEC_CTRL.PSFD */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0.edx, word 9 */
 XEN_CPUFEATURE(SRBDS_CTRL,    9*32+ 9) /*   MSR_MCU_OPT_CTRL and RNGDS_MITG_DIS. */
