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x86/pti: Don't report XenPV as vulnerable

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Xen PV domain kernel is not by design affected by meltdown as it's
enforcing split CR3 itself. Let's not report such systems as "Vulnerable"
in sysfs (we're also already forcing PTI to off in X86_HYPER_XEN_PV cases);
the security of the system ultimately depends on presence of mitigation in
the Hypervisor, which can't be easily detected from DomU; let's report
that.

Reported-and-tested-by: Mike Latimer <mlatimer@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1806180959080.6203@cbobk.fhfr.pm
[ Merge the user-visible string into a single line. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Jiri Kosina 2018-06-18 09:59:54 +02:00 committed by Ingo Molnar
parent 9ffc59d572
commit 6cb2b08ff9
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kernel/cpu/bugs.c
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@ -27,6 +27,7 @@
#include <asm/pgtable.h>
#include <asm/set_memory.h>
#include <asm/intel-family.h>
#include <asm/hypervisor.h>
static void __init spectre_v2_select_mitigation(void);
static void __init ssb_select_mitigation(void);
@ -664,6 +665,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
if (boot_cpu_has(X86_FEATURE_PTI))
return sprintf(buf, "Mitigation: PTI\n");
if (hypervisor_is_type(X86_HYPER_XEN_PV))
return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
break;
case X86_BUG_SPECTRE_V1: