[PATCH 12/12] x86/xpti: add per-domain parameter for controlling xpti

[Juergen Gross <jgross@suse.com>]

Add a per-domain parameter to switch xpti for single pv domains on or
off.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 docs/man/xl.cfg.pod.5.in | 12 +++++++++++-
 xen/arch/x86/pv/domain.c | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/docs/man/xl.cfg.pod.5.in b/docs/man/xl.cfg.pod.5.in
index c97ae77129..524f9f23d4 100644
--- a/docs/man/xl.cfg.pod.5.in
+++ b/docs/man/xl.cfg.pod.5.in
@@ -612,7 +612,17 @@ The following parameter settings are supported:
 
 =over 4
 
-NONE
+=item B<xpti=BOOLEAN>
+
+Override default selection of whether to isolate 64-bit PV guest page
+tables of a domain.
+
+B<true> activates page table isolation even on hardware not vulnerable by
+Meltdown for the domain.
+
+B<false> deactivates page table isolation on all systems for the domain.
+
+Can be modified at runtime.
 
 =back
 
diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c
index 355f320fa3..86d9f8fb67 100644
--- a/xen/arch/x86/pv/domain.c
+++ b/xen/arch/x86/pv/domain.c
@@ -287,6 +287,43 @@ int pv_domain_initialise(struct domain *d)
     return rc;
 }
 
+static int dompar_xpti(const char *s, struct domain *d)
+{
+    switch ( parse_bool(s, NULL) )
+    {
+    case 0:
+        d->arch.pv.xpti = false;
+        break;
+
+    case 1:
+        d->arch.pv.xpti = true;
+        break;
+
+    default:
+        return -EINVAL;
+    }
+
+    switch ( opt_pcid )
+    {
+    case PCID_XPTI:
+        d->arch.pv.pcid = d->arch.pv.xpti;
+        break;
+
+    case PCID_NOXPTI:
+        d->arch.pv.pcid = !d->arch.pv.xpti;
+        break;
+
+    default:
+        break;
+    }
+
+    return 0;
+}
+
+custom_domain_param("xpti",
+                    PARAM_FLAG_RUNTIME | PARAM_FLAG_NOHVM | PARAM_FLAG_NOPV32,
+                    dompar_xpti);
+
 bool __init xpti_pcid_enabled(void)
 {
     return use_invpcid && cpu_has_pcid &&
-- 
2.16.4


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