[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen stable-4.14] x86/spec-ctrl: Add fine-grained cmdline suboptions for primitives
commit e5fd5081e078ec4ac6e0f3b60fe6c1475a3f2e18 Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> AuthorDate: Fri Jul 8 16:44:43 2022 +0100 Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CommitDate: Tue Jul 12 16:31:49 2022 +0100 x86/spec-ctrl: Add fine-grained cmdline suboptions for primitives Support controling the PV/HVM suboption of msr-sc/rsb/md-clear, which previously wasn't possible. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> (cherry picked from commit 27357c394ba6e1571a89105b840ce1c6f026485c) --- docs/misc/xen-command-line.pandoc | 12 +++++-- xen/arch/x86/spec_ctrl.c | 66 +++++++++++++++++++++++++++++++++------ 2 files changed, 66 insertions(+), 12 deletions(-) diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc index 2302cec91f..a84f5c1921 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -2104,7 +2104,8 @@ not be able to control the state of the mitigation. By default SSBD will be mitigated at runtime (i.e `ssbd=runtime`). ### spec-ctrl (x86) -> `= List of [ <bool>, xen=<bool>, {pv,hvm,msr-sc,rsb,md-clear}=<bool>, +> `= List of [ <bool>, xen=<bool>, {pv,hvm}=<bool>, +> {msr-sc,rsb,md-clear}=<bool>|{pv,hvm}=<bool>, > bti-thunk=retpoline|lfence|jmp, {ibrs,ibpb,ssbd,psfd, > eager-fpu,l1d-flush,branch-harden,srb-lock, > unpriv-mmio}=<bool> ]` @@ -2129,12 +2130,17 @@ in place for guests to use. Use of a positive boolean value for either of these options is invalid. -The booleans `pv=`, `hvm=`, `msr-sc=`, `rsb=` and `md-clear=` offer fine +The `pv=`, `hvm=`, `msr-sc=`, `rsb=` and `md-clear=` options offer fine grained control over the primitives by Xen. These impact Xen's ability to -protect itself, and Xen's ability to virtualise support for guests to use. +protect itself, and/or Xen's ability to virtualise support for guests to use. * `pv=` and `hvm=` offer control over all suboptions for PV and HVM guests respectively. +* Each other option can be used either as a plain boolean + (e.g. `spec-ctrl=rsb` to control both the PV and HVM sub-options), or with + `pv=` or `hvm=` subsuboptions (e.g. `spec-ctrl=rsb=no-hvm` to disable HVM + RSB only). + * `msr-sc=` offers control over Xen's support for manipulating `MSR_SPEC_CTRL` on entry and exit. These blocks are necessary to virtualise support for guests and if disabled, guests will be unable to use IBRS/STIBP/SSBD/etc. diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c index 06790897e4..225fe08259 100644 --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -147,20 +147,68 @@ static int __init parse_spec_ctrl(const char *s) opt_rsb_hvm = val; opt_md_clear_hvm = val; } - else if ( (val = parse_boolean("msr-sc", s, ss)) >= 0 ) + else if ( (val = parse_boolean("msr-sc", s, ss)) != -1 ) { - opt_msr_sc_pv = val; - opt_msr_sc_hvm = val; + switch ( val ) + { + case 0: + case 1: + opt_msr_sc_pv = opt_msr_sc_hvm = val; + break; + + case -2: + s += strlen("msr-sc="); + if ( (val = parse_boolean("pv", s, ss)) >= 0 ) + opt_msr_sc_pv = val; + else if ( (val = parse_boolean("hvm", s, ss)) >= 0 ) + opt_msr_sc_hvm = val; + else + default: + rc = -EINVAL; + break; + } } - else if ( (val = parse_boolean("rsb", s, ss)) >= 0 ) + else if ( (val = parse_boolean("rsb", s, ss)) != -1 ) { - opt_rsb_pv = val; - opt_rsb_hvm = val; + switch ( val ) + { + case 0: + case 1: + opt_rsb_pv = opt_rsb_hvm = val; + break; + + case -2: + s += strlen("rsb="); + if ( (val = parse_boolean("pv", s, ss)) >= 0 ) + opt_rsb_pv = val; + else if ( (val = parse_boolean("hvm", s, ss)) >= 0 ) + opt_rsb_hvm = val; + else + default: + rc = -EINVAL; + break; + } } - else if ( (val = parse_boolean("md-clear", s, ss)) >= 0 ) + else if ( (val = parse_boolean("md-clear", s, ss)) != -1 ) { - opt_md_clear_pv = val; - opt_md_clear_hvm = val; + switch ( val ) + { + case 0: + case 1: + opt_md_clear_pv = opt_md_clear_hvm = val; + break; + + case -2: + s += strlen("md-clear="); + if ( (val = parse_boolean("pv", s, ss)) >= 0 ) + opt_md_clear_pv = val; + else if ( (val = parse_boolean("hvm", s, ss)) >= 0 ) + opt_md_clear_hvm = val; + else + default: + rc = -EINVAL; + break; + } } /* Xen's speculative sidechannel mitigation settings. */ -- generated by git-patchbot for /home/xen/git/xen.git#stable-4.14
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