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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH for-4.19] tools/xen-cpuid: switch to use cpu-policy defined names
On Tue, Apr 30, 2024 at 12:37:44PM +0200, Jan Beulich wrote:
> On 30.04.2024 10:29, Roger Pau Monne wrote:
> > Like it was done recently for libxl, switch to using the auto-generated
> > feature
> > names by the processing of cpufeatureset.h, this allows removing the
> > open-coded
> > feature names, and unifies the feature naming with libxl and the hypervisor.
> >
> > Note that leaf names need to be kept, as the current auto-generated data
> > doesn't contain the leaf names.
> >
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > ---
> > Late for 4.19, but I would still like it to be considered for inclusion
> > since
> > it's IMO a nice cleanup and reduces the burden of adding new feature bits
> > into
> > the policy.
>
> I agree, but it's Oleksii's call (now Cc-ed).
>
> > --- a/tools/misc/xen-cpuid.c
> > +++ b/tools/misc/xen-cpuid.c
> > @@ -12,282 +12,33 @@
> >
> > #include <xen-tools/common-macros.h>
> >
> > -static uint32_t nr_features;
> > -
> > -static const char *const str_1d[32] =
> > -{
> > - [ 0] = "fpu", [ 1] = "vme",
> > - [ 2] = "de", [ 3] = "pse",
> > - [ 4] = "tsc", [ 5] = "msr",
> > - [ 6] = "pae", [ 7] = "mce",
> > - [ 8] = "cx8", [ 9] = "apic",
> > - /* [10] */ [11] = "sysenter",
> > - [12] = "mtrr", [13] = "pge",
> > - [14] = "mca", [15] = "cmov",
> > - [16] = "pat", [17] = "pse36",
> > - [18] = "psn", [19] = "clflush",
> > - /* [20] */ [21] = "ds",
> > - [22] = "acpi", [23] = "mmx",
> > - [24] = "fxsr", [25] = "sse",
> > - [26] = "sse2", [27] = "ss",
> > - [28] = "htt", [29] = "tm",
> > - [30] = "ia64", [31] = "pbe",
> > -};
> > -
> > -static const char *const str_1c[32] =
> > -{
> > - [ 0] = "sse3", [ 1] = "pclmulqdq",
> > - [ 2] = "dtes64", [ 3] = "monitor",
> > - [ 4] = "ds-cpl", [ 5] = "vmx",
> > - [ 6] = "smx", [ 7] = "est",
> > - [ 8] = "tm2", [ 9] = "ssse3",
> > - [10] = "cntx-id", [11] = "sdgb",
> > - [12] = "fma", [13] = "cx16",
> > - [14] = "xtpr", [15] = "pdcm",
> > - /* [16] */ [17] = "pcid",
> > - [18] = "dca", [19] = "sse41",
> > - [20] = "sse42", [21] = "x2apic",
> > - [22] = "movebe", [23] = "popcnt",
> > - [24] = "tsc-dl", [25] = "aesni",
> > - [26] = "xsave", [27] = "osxsave",
> > - [28] = "avx", [29] = "f16c",
> > - [30] = "rdrnd", [31] = "hyper",
> > -};
> > -
> > -static const char *const str_e1d[32] =
> > -{
> > - [ 0] = "fpu", [ 1] = "vme",
> > - [ 2] = "de", [ 3] = "pse",
> > - [ 4] = "tsc", [ 5] = "msr",
> > - [ 6] = "pae", [ 7] = "mce",
> > - [ 8] = "cx8", [ 9] = "apic",
> > - /* [10] */ [11] = "syscall",
> > - [12] = "mtrr", [13] = "pge",
> > - [14] = "mca", [15] = "cmov",
> > - [16] = "fcmov", [17] = "pse36",
> > - /* [18] */ [19] = "mp",
> > - [20] = "nx", /* [21] */
> > - [22] = "mmx+", [23] = "mmx",
> > - [24] = "fxsr", [25] = "fxsr+",
> > - [26] = "pg1g", [27] = "rdtscp",
> > - /* [28] */ [29] = "lm",
> > - [30] = "3dnow+", [31] = "3dnow",
> > -};
> > -
> > -static const char *const str_e1c[32] =
> > -{
> > - [ 0] = "lahf-lm", [ 1] = "cmp",
> > - [ 2] = "svm", [ 3] = "extapic",
> > - [ 4] = "cr8d", [ 5] = "lzcnt",
> > - [ 6] = "sse4a", [ 7] = "msse",
> > - [ 8] = "3dnowpf", [ 9] = "osvw",
> > - [10] = "ibs", [11] = "xop",
> > - [12] = "skinit", [13] = "wdt",
> > - /* [14] */ [15] = "lwp",
> > - [16] = "fma4", [17] = "tce",
> > - /* [18] */ [19] = "nodeid",
> > - /* [20] */ [21] = "tbm",
> > - [22] = "topoext", [23] = "perfctr-core",
> > - [24] = "perfctr-nb", /* [25] */
> > - [26] = "dbx", [27] = "perftsc",
> > - [28] = "pcx-l2i", [29] = "monitorx",
> > - [30] = "addr-msk-ext",
> > -};
> > -
> > -static const char *const str_7b0[32] =
> > -{
> > - [ 0] = "fsgsbase", [ 1] = "tsc-adj",
> > - [ 2] = "sgx", [ 3] = "bmi1",
> > - [ 4] = "hle", [ 5] = "avx2",
> > - [ 6] = "fdp-exn", [ 7] = "smep",
> > - [ 8] = "bmi2", [ 9] = "erms",
> > - [10] = "invpcid", [11] = "rtm",
> > - [12] = "pqm", [13] = "depfpp",
> > - [14] = "mpx", [15] = "pqe",
> > - [16] = "avx512f", [17] = "avx512dq",
> > - [18] = "rdseed", [19] = "adx",
> > - [20] = "smap", [21] = "avx512-ifma",
> > - [22] = "pcommit", [23] = "clflushopt",
> > - [24] = "clwb", [25] = "proc-trace",
> > - [26] = "avx512pf", [27] = "avx512er",
> > - [28] = "avx512cd", [29] = "sha",
> > - [30] = "avx512bw", [31] = "avx512vl",
> > -};
> > -
> > -static const char *const str_Da1[32] =
> > -{
> > - [ 0] = "xsaveopt", [ 1] = "xsavec",
> > - [ 2] = "xgetbv1", [ 3] = "xsaves",
> > -};
> > -
> > -static const char *const str_7c0[32] =
> > -{
> > - [ 0] = "prefetchwt1", [ 1] = "avx512-vbmi",
> > - [ 2] = "umip", [ 3] = "pku",
> > - [ 4] = "ospke", [ 5] = "waitpkg",
> > - [ 6] = "avx512-vbmi2", [ 7] = "cet-ss",
> > - [ 8] = "gfni", [ 9] = "vaes",
> > - [10] = "vpclmulqdq", [11] = "avx512-vnni",
> > - [12] = "avx512-bitalg",
> > - [14] = "avx512-vpopcntdq",
> > -
> > - [22] = "rdpid",
> > - /* 24 */ [25] = "cldemote",
> > - /* 26 */ [27] = "movdiri",
> > - [28] = "movdir64b", [29] = "enqcmd",
> > - [30] = "sgx-lc", [31] = "pks",
> > -};
> > -
> > -static const char *const str_e7d[32] =
> > -{
> > - /* 6 */ [ 7] = "hw-pstate",
> > - [ 8] = "itsc", [ 9] = "cpb",
> > - [10] = "efro",
> > -};
> > -
> > -static const char *const str_e8b[32] =
> > -{
> > - [ 0] = "clzero",
> > - [ 2] = "rstr-fp-err-ptrs",
> > -
> > - /* [ 8] */ [ 9] = "wbnoinvd",
> > -
> > - [12] = "ibpb",
> > - [14] = "ibrs", [15] = "amd-stibp",
> > - [16] = "ibrs-always", [17] = "stibp-always",
> > - [18] = "ibrs-fast", [19] = "ibrs-same-mode",
> > -
> > - [20] = "no-lmsl",
> > - /* [22] */ [23] = "ppin",
> > - [24] = "amd-ssbd", [25] = "virt-ssbd",
> > - [26] = "ssb-no",
> > - [28] = "psfd", [29] = "btc-no",
> > - [30] = "ibpb-ret",
> > -};
> > -
> > -static const char *const str_7d0[32] =
> > -{
> > - [ 2] = "avx512-4vnniw", [ 3] = "avx512-4fmaps",
> > - [ 4] = "fsrm",
> > -
> > - [ 8] = "avx512-vp2intersect", [ 9] = "srbds-ctrl",
> > - [10] = "md-clear", [11] = "rtm-always-abort",
> > - /* 12 */ [13] = "tsx-force-abort",
> > - [14] = "serialize", [15] = "hybrid",
> > - [16] = "tsxldtrk",
> > - [18] = "pconfig",
> > - [20] = "cet-ibt",
> > - /* 22 */ [23] = "avx512-fp16",
> > -
> > - [26] = "ibrsb", [27] = "stibp",
> > - [28] = "l1d-flush", [29] = "arch-caps",
> > - [30] = "core-caps", [31] = "ssbd",
> > -};
> > -
> > -static const char *const str_7a1[32] =
> > -{
> > - [ 0] = "sha512", [ 1] = "sm3",
> > - [ 2] = "sm4",
> > - [ 4] = "avx-vnni", [ 5] = "avx512-bf16",
> > -
> > - [10] = "fzrm", [11] = "fsrs",
> > - [12] = "fsrcs",
> > -
> > - /* 18 */ [19] = "wrmsrns",
> > -
> > - /* 22 */ [23] = "avx-ifma",
> > -};
> > +#include <xen/lib/x86/cpu-policy.h>
> >
> > -static const char *const str_e21a[32] =
> > -{
> > - [ 0] = "no-nest-bp", [ 1] = "fs-gs-ns",
> > - [ 2] = "lfence+",
> > - [ 6] = "nscb",
> > - [ 8] = "auto-ibrs",
> > - [10] = "amd-fsrs", [11] = "amd-fsrc",
> > -
> > - /* 16 */ [17] = "cpuid-user-dis",
> > - [18] = "epsf", [19] = "fsrsc",
> > - [20] = "amd-prefetchi",
> > -
> > - /* 26 */ [27] = "sbpb",
> > - [28] = "ibpb-brtype", [29] = "srso-no",
> > -};
> > -
> > -static const char *const str_7b1[32] =
> > -{
> > - [ 0] = "ppin",
> > -};
> > -
> > -static const char *const str_7c1[32] =
> > -{
> > -};
> > -
> > -static const char *const str_7d1[32] =
> > -{
> > - [ 4] = "avx-vnni-int8", [ 5] = "avx-ne-convert",
> > -
> > - [10] = "avx-vnni-int16",
> > -
> > - [14] = "prefetchi",
> > -
> > - [18] = "cet-sss",
> > -};
> > -
> > -static const char *const str_7d2[32] =
> > -{
> > - [ 0] = "intel-psfd", [ 1] = "ipred-ctrl",
> > - [ 2] = "rrsba-ctrl", [ 3] = "ddp-ctrl",
> > - [ 4] = "bhi-ctrl", [ 5] = "mcdt-no",
> > -};
> > -
> > -static const char *const str_m10Al[32] =
> > -{
> > - [ 0] = "rdcl-no", [ 1] = "eibrs",
> > - [ 2] = "rsba", [ 3] = "skip-l1dfl",
> > - [ 4] = "intel-ssb-no", [ 5] = "mds-no",
> > - [ 6] = "if-pschange-mc-no", [ 7] = "tsx-ctrl",
> > - [ 8] = "taa-no", [ 9] = "mcu-ctrl",
> > - [10] = "misc-pkg-ctrl", [11] = "energy-ctrl",
> > - [12] = "doitm", [13] = "sbdr-ssdp-no",
> > - [14] = "fbsdp-no", [15] = "psdp-no",
> > - /* 16 */ [17] = "fb-clear",
> > - [18] = "fb-clear-ctrl", [19] = "rrsba",
> > - [20] = "bhi-no", [21] = "xapic-status",
> > - /* 22 */ [23] = "ovrclk-status",
> > - [24] = "pbrsb-no", [25] = "gds-ctrl",
> > - [26] = "gds-no", [27] = "rfds-no",
> > - [28] = "rfds-clear",
> > -};
> > -
> > -static const char *const str_m10Ah[32] =
> > -{
> > -};
> > +static uint32_t nr_features;
> >
> > static const struct {
> > const char *name;
> > const char *abbr;
> > - const char *const *strs;
>
> While how you're doing it looks all technically correct (so even without
> changes I may later ack this as is), I'm still a little puzzled. I was
> kind of expecting xen-cpuid.py to be extended to supply more another (set
> of) #define(s) more suitable for use here. In particular, while
> performance surely isn't of much concern in this tool, ...
>
> > @@ -301,21 +52,32 @@ static const char *const fs_names[] = {
> > [XEN_SYSCTL_cpu_featureset_hvm_max] = "HVM Max",
> > };
> >
> > -static void dump_leaf(uint32_t leaf, const char *const *strs)
> > +static const char *find_name(unsigned int index)
> > {
> > - unsigned i;
> > + static const struct feature_name {
> > + const char *name;
> > + unsigned int bit;
> > + } feature_names[] = INIT_FEATURE_NAMES;
> > + unsigned int i;
> >
> > - if ( !strs )
> > - {
> > - printf(" ???");
> > - return;
> > - }
> > + for ( i = 0; i < ARRAY_SIZE(feature_names); i++ )
> > + if ( feature_names[i].bit == index )
> > + return feature_names[i].name;
>
> ... a linear search, repeated perhaps hundreds of times, looks still a
> little odd to me.
I didn't benchmark what kind of performance impact this change would
have on the tool, but I didn't think it was that relevant, as this is
a diagnostic/debug tool, and hence performance (unless it took seconds
to execute) shouldn't be that important.
I could switch to a non-const array and sort it at the start in order
to do a binary search, but that might be over engineering it.
> > +static void dump_leaf(uint32_t leaf, unsigned int index)
> > +{
> > + unsigned i;
> >
> > for ( i = 0; i < 32; ++i )
> > if ( leaf & (1u << i) )
> > {
> > - if ( strs[i] )
> > - printf(" %s", strs[i]);
> > + const char *name = find_name(index * 32 + i);
> > +
> > + if ( name )
> > + printf(" %s", name);
> > else
> > printf(" <%u>", i);
> > }
> > @@ -326,6 +88,7 @@ static void decode_featureset(const uint32_t *features,
> > const char *name,
> > bool detail)
> > {
> > + static const uint32_t known_features[] = INIT_KNOWN_FEATURES;
> > unsigned int i;
>
> So this variable exists solely to ...
>
> > @@ -336,11 +99,14 @@ static void decode_featureset(const uint32_t *features,
> > if ( !detail )
> > return;
> >
> > - for ( i = 0; i < length && i < ARRAY_SIZE(decodes); ++i )
> > + /* Ensure leaf names stay in sync with the policy leaf count. */
> > + BUILD_BUG_ON(ARRAY_SIZE(known_features) != ARRAY_SIZE(leaf_names));
>
> ... calculate its size here. Thus relying on the compiler to not flag
> such effectively unused static const variables.
I wondered whether to add the unused attribute, but seeing as gitlab
didn't complain I've forgot to add it. I could add it.
> > + for ( i = 0; i < length && i < ARRAY_SIZE(leaf_names); ++i )
> > {
> > - printf(" [%02u] %-"COL_ALIGN"s", i, decodes[i].name ?:
> > "<UNKNOWN>");
> > - if ( decodes[i].name )
> > - dump_leaf(features[i], decodes[i].strs);
> > + printf(" [%02u] %-"COL_ALIGN"s", i, leaf_names[i].name ?:
> > "<UNKNOWN>");
>
> I realize you merely transform what has been there, but do we really
> need this fallback to "<UNKNOWN>" here and ...
>
> > @@ -355,8 +121,8 @@ static void dump_info(xc_interface *xch, bool detail)
> > if ( !detail )
> > {
> > printf(" %"COL_ALIGN"s ", "KEY");
> > - for ( i = 0; i < ARRAY_SIZE(decodes); ++i )
> > - printf("%-8s ", decodes[i].abbr ?: "???");
> > + for ( i = 0; i < ARRAY_SIZE(leaf_names); ++i )
> > + printf("%-8s ", leaf_names[i].abbr ?: "???");
>
> to "???" here? The table entries are all fully populated, and I don't
> see why future ones wouldn't be. IOW I don't think I see what good this
> is doing us, when at the same time it doesn't help readability.
TBH I wasn't sure about the intention here, so decided to leave those
alone. The iteration is done against leaf_names (or decodes), so this
would mean there's an array entry in the table that explicitly has
name or abbr fields unset, which would be weird to me.
But again without knowing the original intention of those, and the
change being tangential to the purpose I've decided to leave those
alone.
Thanks, Roger.
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