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openSUSE:Leap:15.0:Staging:E
xen
5a5e3a4e-7-x86-cmdline-opt-to-disable-IBRS-IBPB...
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File 5a5e3a4e-7-x86-cmdline-opt-to-disable-IBRS-IBPB-STIBP.patch of Package xen
# Commit 7850b1c00749df834ea2ad0c1f5d9364c4838795 # Date 2018-01-16 17:45:50 +0000 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> x86/cmdline: Introduce a command line option to disable IBRS/IBPB, STIBP and IBPB Instead of gaining yet another top level boolean, introduce a more generic cpuid= option. Also introduce a helper function to parse a generic boolean value. This is part of XSA-254. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> # Commit ac37ec1ddef234eeba6f438c29ff687c64962ebd # Date 2018-01-31 10:47:12 +0000 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> xen/cmdline: Fix parse_boolean() for unadorned values A command line such as "cpuid=no-ibrsb,no-stibp" tickles a bug in parse_boolean() because the separating comma fails the NUL case. Instead, check for slen == nlen which accounts for the boundary (if any) passed via the 'e' parameter. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- trunk.orig/docs/misc/xen-command-line.markdown 2018-02-01 11:40:54.706665840 +0100 +++ trunk/docs/misc/xen-command-line.markdown 2018-02-01 00:00:00.000000000 +0100 @@ -471,6 +471,18 @@ choice of `dom0-kernel` is deprecated an respectively. * `verbose` option can be included as a string or also as `verbose=<integer>` +### cpuid (x86) +> `= List of comma separated booleans` + +This option allows for fine tuning of the facilities Xen will use, after +accounting for hardware capabilities as enumerated via CPUID. + +Currently accepted: + +The Speculation Control hardware features `ibrsb`, `stibp`, `ibpb` are used by +default if avaiable. They can be ignored, e.g. `no-ibrsb`, at which point Xen +won't use them itself, and won't offer them to guests. + ### cpuid\_mask\_cpu (AMD only) > `= fam_0f_rev_c | fam_0f_rev_d | fam_0f_rev_e | fam_0f_rev_f | fam_0f_rev_g | fam_10_rev_b | fam_10_rev_c | fam_11_rev_b` --- trunk.orig/xen/arch/x86/cpuid.c 2018-02-01 11:40:54.706665840 +0100 +++ trunk/xen/arch/x86/cpuid.c 2018-02-01 00:00:00.000000000 +0100 @@ -18,6 +18,41 @@ static const uint32_t hvm_shadow_feature static const uint32_t hvm_hap_featuremask[] = INIT_HVM_HAP_FEATURES; static const uint32_t deep_features[] = INIT_DEEP_FEATURES; +static int __init parse_xen_cpuid(const char *s) +{ + const char *ss; + int val, rc = 0; + + do { + ss = strchr(s, ','); + if ( !ss ) + ss = strchr(s, '\0'); + + if ( (val = parse_boolean("ibpb", s, ss)) >= 0 ) + { + if ( !val ) + setup_clear_cpu_cap(X86_FEATURE_IBPB); + } + else if ( (val = parse_boolean("ibrsb", s, ss)) >= 0 ) + { + if ( !val ) + setup_clear_cpu_cap(X86_FEATURE_IBRSB); + } + else if ( (val = parse_boolean("stibp", s, ss)) >= 0 ) + { + if ( !val ) + setup_clear_cpu_cap(X86_FEATURE_STIBP); + } + else + rc = -EINVAL; + + s = ss + 1; + } while ( *ss ); + + return rc; +} +custom_param("cpuid", parse_xen_cpuid); + #define EMPTY_LEAF ((struct cpuid_leaf){}) static void zero_leaves(struct cpuid_leaf *l, unsigned int first, unsigned int last) --- trunk.orig/xen/common/kernel.c 2018-02-01 11:40:54.706665840 +0100 +++ trunk/xen/common/kernel.c 2018-02-01 11:40:25.000000000 +0100 @@ -244,6 +244,33 @@ int parse_bool(const char *s, const char return -1; } +int parse_boolean(const char *name, const char *s, const char *e) +{ + size_t slen, nlen; + int val = !!strncmp(s, "no-", 3); + + if ( !val ) + s += 3; + + slen = e ? ({ ASSERT(e >= s); e - s; }) : strlen(s); + nlen = strlen(name); + + /* Does s now start with name? */ + if ( slen < nlen || strncmp(s, name, nlen) ) + return -1; + + /* Exact, unadorned name? Result depends on the 'no-' prefix. */ + if ( slen == nlen ) + return val; + + /* =$SOMETHING? Defer to the regular boolean parsing. */ + if ( s[nlen] == '=' ) + return parse_bool(&s[nlen + 1], e); + + /* Unrecognised. Give up. */ + return -1; +} + unsigned int tainted; /** --- trunk.orig/xen/include/xen/lib.h 2018-02-01 11:40:54.706665840 +0100 +++ trunk/xen/include/xen/lib.h 2018-02-01 00:00:00.000000000 +0100 @@ -74,6 +74,13 @@ void cmdline_parse(const char *cmdline); int runtime_parse(const char *line); int parse_bool(const char *s, const char *e); +/** + * Given a specific name, parses a string of the form: + * [no-]$NAME[=...] + * returning 0 or 1 for a recognised boolean, or -1 for an error. + */ +int parse_boolean(const char *name, const char *s, const char *e); + /*#define DEBUG_TRACE_DUMP*/ #ifdef DEBUG_TRACE_DUMP extern void debugtrace_dump(void);
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