[Xen-changelog] [xen staging-4.9] x86: Make "spec-ctrl=no" a global disable of all mitigations

[patchbot@xxxxxxx]

commit c95088f090e8c1c5207f9da1d3c5bcf72af41cc7
Author:     Jan Beulich <JBeulich@xxxxxxxx>
AuthorDate: Mon Aug 13 05:07:23 2018 -0600
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Aug 14 17:20:02 2018 +0100

    x86: Make "spec-ctrl=no" a global disable of all mitigations
    
    In order to have a simple and easy to remember means to suppress all the
    more or less recent workarounds for hardware vulnerabilities, force
    settings not controlled by "spec-ctrl=" also to their original defaults,
    unless they've been forced to specific values already by earlier command
    line options.
    
    This is part of XSA-273.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    (cherry picked from commit d8800a82c3840b06b17672eddee4878bbfdacc6d)
---
 docs/misc/xen-command-line.markdown | 13 +++++++++----
 xen/arch/x86/spec_ctrl.c            |  9 +++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown 
b/docs/misc/xen-command-line.markdown
index e2787fc71e..60094504f4 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1691,10 +1691,15 @@ extreme care.**
 
 An overall boolean value, `spec-ctrl=no`, can be specified to turn off all
 mitigations, including pieces of infrastructure used to virtualise certain
-mitigation features for guests.  Alternatively, a slightly more restricted
-`spec-ctrl=no-xen` can be used to turn off all of Xen's mitigations, while
-leaving the virtualisation support in place for guests to use.  Use of a
-positive boolean value for either of these options is invalid.
+mitigation features for guests.  This also includes settings which `xpti`,
+`smt`, `pv-l1tf` control, unless the respective option(s) have been
+specified earlier on the command line.
+
+Alternatively, a slightly more restricted `spec-ctrl=no-xen` can be used to
+turn off all of Xen's mitigations, while leaving the virtualisation support
+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=` and `rsb=` offer fine grained control
 over the alternative blocks used by Xen.  These impact Xen's ability to
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index f4992d936d..60c65222d2 100644
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -117,6 +117,15 @@ static int __init parse_spec_ctrl(char *s)
 
             opt_eager_fpu = 0;
 
+            if ( opt_xpti < 0 )
+                opt_xpti = 0;
+
+            if ( opt_smt < 0 )
+                opt_smt = 1;
+
+            if ( opt_pv_l1tf < 0 )
+                opt_pv_l1tf = 0;
+
         disable_common:
             opt_rsb_pv = false;
             opt_rsb_hvm = false;
--
generated by git-patchbot for /home/xen/git/xen.git#staging-4.9

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