x86/spec-ctrl: Enumerations for DDP controls

https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/data-dependent-prefetcher.html

We should offer DDP-CTRL to guests, but I'm not sure when it is appearing in
hardware, and it's not massively urgent - the DDP behaviour is mostly sane
(having been designed in a post-spectre world) and this is a just-in-case
control.

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

tools/libs/light/libxl_cpuid.c

@@ -242,6 +242,7 @@ int libxl_cpuid_parse_config(libxl_cpuid_policy_list *cpuid, const char* str)
         {"intel-psfd",   0x00000007,  2, CPUID_REG_EDX,  0,  1},
         {"ipred-ctrl",   0x00000007,  2, CPUID_REG_EDX,  1,  1},
         {"rrsba-ctrl",   0x00000007,  2, CPUID_REG_EDX,  2,  1},
+        {"ddp-ctrl",     0x00000007,  2, CPUID_REG_EDX,  3,  1},
         {"bhi-ctrl",     0x00000007,  2, CPUID_REG_EDX,  4,  1},
         {"mcdt-no",      0x00000007,  2, CPUID_REG_EDX,  5,  1},
 

tools/misc/xen-cpuid.c

@@ -216,7 +216,7 @@ static const char *const str_7d1[32] =
 static const char *const str_7d2[32] =
 {
     [ 0] = "intel-psfd",    [ 1] = "ipred-ctrl",
-    [ 2] = "rrsba-ctrl",
+    [ 2] = "rrsba-ctrl",    [ 3] = "ddp-ctrl",
     [ 4] = "bhi-ctrl",      [ 5] = "mcdt-no",
 };
 

xen/arch/x86/include/asm/msr-index.h

@@ -41,6 +41,7 @@
 #define  SPEC_CTRL_RRSBA_DIS_U              (_AC(1, ULL) <<  5)
 #define  SPEC_CTRL_RRSBA_DIS_S              (_AC(1, ULL) <<  6)
 #define  SPEC_CTRL_PSFD                     (_AC(1, ULL) <<  7)
+#define  SPEC_CTRL_DDP_DIS_U                (_AC(1, ULL) <<  8)
 #define  SPEC_CTRL_BHI_DIS_S                (_AC(1, ULL) << 10)
 
 #define MSR_PRED_CMD                        0x00000049

xen/include/public/arch-x86/cpufeatureset.h

@@ -294,6 +294,7 @@ 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) /*   MSR_SPEC_CTRL.IPRED_DIS_* */
 XEN_CPUFEATURE(RRSBA_CTRL,         13*32+ 2) /*   MSR_SPEC_CTRL.RRSBA_DIS_* */
+XEN_CPUFEATURE(DDP_CTRL,           13*32+ 3) /*   MSR_SPEC_CTRL.DDP_DIS_U */
 XEN_CPUFEATURE(BHI_CTRL,           13*32+ 4) /*   MSR_SPEC_CTRL.BHI_DIS_S */
 XEN_CPUFEATURE(MCDT_NO,            13*32+ 5) /*A  MCDT_NO */