diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2018-01-31 17:47:03 -0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-02-01 10:59:10 +0100 |
| commit | 085331dfc6bbe3501fb936e657331ca943827600 (patch) | |
| tree | 0d232c6ca05ee32350962d32d351520394dae0c9 /arch/x86/kvm | |
| parent | 12c69f1e94c89d40696e83804dd2f0965b5250cd (diff) | |
x86/kvm: Update spectre-v1 mitigation
Commit 75f139aaf896 "KVM: x86: Add memory barrier on vmcs field lookup"
added a raw 'asm("lfence");' to prevent a bounds check bypass of
'vmcs_field_to_offset_table'.
The lfence can be avoided in this path by using the array_index_nospec()
helper designed for these types of fixes.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andrew Honig <ahonig@google.com>
Cc: kvm@vger.kernel.org
Cc: Jim Mattson <jmattson@google.com>
Link: https://lkml.kernel.org/r/151744959670.6342.3001723920950249067.stgit@dwillia2-desk3.amr.corp.intel.com
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a8b96dc4cd83..28942823cc3a 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -34,6 +34,7 @@ #include <linux/tboot.h> #include <linux/hrtimer.h> #include <linux/frame.h> +#include <linux/nospec.h> #include "kvm_cache_regs.h" #include "x86.h" @@ -898,21 +899,18 @@ static const unsigned short vmcs_field_to_offset_table[] = { static inline short vmcs_field_to_offset(unsigned long field) { - BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) > SHRT_MAX); + const size_t size = ARRAY_SIZE(vmcs_field_to_offset_table); + unsigned short offset; - if (field >= ARRAY_SIZE(vmcs_field_to_offset_table)) + BUILD_BUG_ON(size > SHRT_MAX); + if (field >= size) return -ENOENT; - /* - * FIXME: Mitigation for CVE-2017-5753. To be replaced with a - * generic mechanism. - */ - asm("lfence"); - - if (vmcs_field_to_offset_table[field] == 0) + field = array_index_nospec(field, size); + offset = vmcs_field_to_offset_table[field]; + if (offset == 0) return -ENOENT; - - return vmcs_field_to_offset_table[field]; + return offset; } static inline struct vmcs12 *get_vmcs12(struct kvm_vcpu *vcpu) |