[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen staging-4.10] common/gnttab: Introduce command line feature controls
commit 9e7ee9478d545ca1b7ff3a7732ca8e9ab7d8f212 Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> AuthorDate: Mon Aug 13 19:32:01 2018 +0100 Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CommitDate: Tue Aug 14 17:16:28 2018 +0100 common/gnttab: Introduce command line feature controls This patch was originally released as part of XSA-226. It retains the same command line syntax (as various downstreams are mitigating XSA-226 using this mechanism) but the defaults have been updated due to the revised XSA-226 patched, after which transitive grants are believed to functioning properly. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> (cherry picked from commit dc96c65ed6d7ffd4c95487373df708d97443cf77) --- docs/misc/xen-command-line.markdown | 13 ++++++++++++ xen/common/grant_table.c | 42 ++++++++++++++++++++++++++++++++++++- 2 files changed, 54 insertions(+), 1 deletion(-) diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown index dba37e2e53..30bc9208da 100644 --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -920,6 +920,19 @@ Controls EPT related features. Specify which console gdbstub should use. See **console**. +### gnttab +> `= List of [ max-ver:<integer>, transitive=<bool> ]` + +> Default: `gnttab=max-ver:2,transitive` + +Control various aspects of the grant table behaviour available to guests. + +* `max-ver` Select the maximum grant table version to offer to guests. Valid +version are 1 and 2. +* `transitive` Permit or disallow the use of transitive grants. Note that the +use of grant table v2 without transitive grants is an ABI breakage from the +guests point of view. + ### gnttab\_max\_frames > `= <integer>` diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c index 7650e6d449..22360ed41e 100644 --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -97,6 +97,41 @@ static unsigned int __read_mostly max_maptrack_frames = DEFAULT_MAX_MAPTRACK_FRAMES; integer_runtime_param("gnttab_max_maptrack_frames", max_maptrack_frames); +static unsigned int __read_mostly opt_gnttab_max_version = 2; +static bool __read_mostly opt_transitive_grants = true; + +static int __init parse_gnttab(const char *s) +{ + const char *ss, *e; + int val, rc = 0; + + do { + ss = strchr(s, ','); + if ( !ss ) + ss = strchr(s, '\0'); + + if ( !strncmp(s, "max-ver:", 8) || + !strncmp(s, "max_ver:", 8) ) /* Alias for original XSA-226 patch */ + { + long ver = simple_strtol(s + 8, &e, 10); + + if ( e == ss && ver >= 1 && ver <= 2 ) + opt_gnttab_max_version = ver; + else + rc = -EINVAL; + } + else if ( (val = parse_boolean("transitive", s, ss)) >= 0 ) + opt_transitive_grants = val; + else + rc = -EINVAL; + + s = ss + 1; + } while ( *ss ); + + return rc; +} +custom_param("gnttab", parse_gnttab); + /* * Note that the three values below are effectively part of the ABI, even if * we don't need to make them a formal part of it: A guest suspended for @@ -2725,7 +2760,8 @@ static int gnttab_copy_claim_buf(const struct gnttab_copy *op, current->domain->domain_id, buf->read_only, &buf->frame, &buf->page, - &buf->ptr.offset, &buf->len, true); + &buf->ptr.offset, &buf->len, + opt_transitive_grants); if ( rc != GNTST_okay ) goto out; buf->ptr.u.ref = ptr->u.ref; @@ -2927,6 +2963,10 @@ gnttab_set_version(XEN_GUEST_HANDLE_PARAM(gnttab_set_version_t) uop) if ( op.version != 1 && op.version != 2 ) goto out; + res = -ENOSYS; + if ( op.version == 2 && opt_gnttab_max_version == 1 ) + goto out; /* Behave as before set_version was introduced. */ + res = 0; if ( gt->gt_version == op.version ) goto out; -- generated by git-patchbot for /home/xen/git/xen.git#staging-4.10 _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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