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authorPawan Gupta <pawan.kumar.gupta@linux.intel.com>2020-07-16 22:23:59 +0300
committerIngo Molnar <mingo@kernel.org>2020-08-07 02:32:00 +0300
commitf29dfa53cc8ae6ad93bae619bcc0bf45cab344f7 (patch)
tree75773c72df86d8df4a61c1f6b987b01dbfa2861b /arch/x86
parent76d10256a97a7cab72b123d54b766a3c17da658c (diff)
downloadlinux-f29dfa53cc8ae6ad93bae619bcc0bf45cab344f7.tar.xz
x86/bugs/multihit: Fix mitigation reporting when VMX is not in use
On systems that have virtualization disabled or unsupported, sysfs mitigation for X86_BUG_ITLB_MULTIHIT is reported incorrectly as: $ cat /sys/devices/system/cpu/vulnerabilities/itlb_multihit KVM: Vulnerable System is not vulnerable to DoS attack from a rogue guest when virtualization is disabled or unsupported in the hardware. Change the mitigation reporting for these cases. Fixes: b8e8c8303ff2 ("kvm: mmu: ITLB_MULTIHIT mitigation") Reported-by: Nelson Dsouza <nelson.dsouza@linux.intel.com> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/0ba029932a816179b9d14a30db38f0f11ef1f166.1594925782.git.pawan.kumar.gupta@linux.intel.com
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/bugs.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index f0b743a2fe9c..d3f0db463f96 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -31,6 +31,7 @@
#include <asm/intel-family.h>
#include <asm/e820/api.h>
#include <asm/hypervisor.h>
+#include <asm/tlbflush.h>
#include "cpu.h"
@@ -1549,7 +1550,12 @@ static ssize_t l1tf_show_state(char *buf)
static ssize_t itlb_multihit_show_state(char *buf)
{
- if (itlb_multihit_kvm_mitigation)
+ if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+ !boot_cpu_has(X86_FEATURE_VMX))
+ return sprintf(buf, "KVM: Mitigation: VMX unsupported\n");
+ else if (!(cr4_read_shadow() & X86_CR4_VMXE))
+ return sprintf(buf, "KVM: Mitigation: VMX disabled\n");
+ else if (itlb_multihit_kvm_mitigation)
return sprintf(buf, "KVM: Mitigation: Split huge pages\n");
else
return sprintf(buf, "KVM: Vulnerable\n");