Subject: x86/spec-ctrl: Enumeration for MMIO Stale Data controls
From: Andrew Cooper <[email-masked]>

The three *_NO bits indicate non-susceptibility to the SSDP, FBSDP and PSDP
data movement primitives.

FB_CLEAR indicates that the VERW instruction has re-gained it's Fill Buffer
flushing side effect.  This is only enumerated on parts where VERW had
previously lost it's flushing side effect due to the MDS/TAA vulnerabilities
being fixed in hardware.

FB_CLEAR_CTRL is available on a subset of FB_CLEAR parts where the Fill Buffer
clearing side effect of VERW can be turned off for performance reasons.

This is part of XSA-404.

Signed-off-by: Andrew Cooper <[email-masked]>
Reviewed-by: Roger Pau Monné <[email-masked]>

diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index 38e1f1098210..fd36927ba1cb 100644
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -318,7 +318,7 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps)
     printk("Speculative mitigation facilities:\n");
 
     /* Hardware features which pertain to speculative mitigations. */
-    printk("  Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
+    printk("  Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
            (_7d0 & cpufeat_mask(X86_FEATURE_IBRSB)) ? " IBRS/IBPB" : "",
            (_7d0 & cpufeat_mask(X86_FEATURE_STIBP)) ? " STIBP"     : "",
            (_7d0 & cpufeat_mask(X86_FEATURE_L1D_FLUSH)) ? " L1D_FLUSH" : "",
@@ -333,7 +333,12 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps)
            (caps & ARCH_CAPS_SSB_NO)                ? " SSB_NO"    : "",
            (caps & ARCH_CAPS_MDS_NO)                ? " MDS_NO"    : "",
            (caps & ARCH_CAPS_TSX_CTRL)              ? " TSX_CTRL"  : "",
-           (caps & ARCH_CAPS_TAA_NO)                ? " TAA_NO"    : "");
+           (caps & ARCH_CAPS_TAA_NO)                ? " TAA_NO"    : "",
+           (caps & ARCH_CAPS_SBDR_SSDP_NO)          ? " SBDR_SSDP_NO" : "",
+           (caps & ARCH_CAPS_FBSDP_NO)              ? " FBSDP_NO"  : "",
+           (caps & ARCH_CAPS_PSDP_NO)               ? " PSDP_NO"   : "",
+           (caps & ARCH_CAPS_FB_CLEAR)              ? " FB_CLEAR"  : "",
+           (caps & ARCH_CAPS_FB_CLEAR_CTRL)         ? " FB_CLEAR_CTRL" : "");
 
     /* Compiled-in support which pertains to mitigations. */
     if ( IS_ENABLED(CONFIG_INDIRECT_THUNK) || IS_ENABLED(CONFIG_SHADOW_PAGING) )
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index ba9e90af210b..2a80660d849d 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -55,6 +55,11 @@
 #define ARCH_CAPS_IF_PSCHANGE_MC_NO	(_AC(1, ULL) << 6)
 #define ARCH_CAPS_TSX_CTRL		(_AC(1, ULL) << 7)
 #define ARCH_CAPS_TAA_NO		(_AC(1, ULL) << 8)
+#define ARCH_CAPS_SBDR_SSDP_NO		(_AC(1, ULL) << 13)
+#define ARCH_CAPS_FBSDP_NO		(_AC(1, ULL) << 14)
+#define ARCH_CAPS_PSDP_NO		(_AC(1, ULL) << 15)
+#define ARCH_CAPS_FB_CLEAR		(_AC(1, ULL) << 17)
+#define ARCH_CAPS_FB_CLEAR_CTRL		(_AC(1, ULL) << 18)
 
 #define MSR_FLUSH_CMD			0x0000010b
 #define FLUSH_CMD_L1D			(_AC(1, ULL) << 0)