This is a note to let you know that I've just added the patch titled
x86/kvm: Update spectre-v1 mitigation
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: x86kvm_Update_spectre-v1_mitigation.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
Subject: x86/kvm: Update spectre-v1 mitigation From: Dan Williams dan.j.williams@intel.com Date: Wed Jan 31 17:47:03 2018 -0800
From: Dan Williams dan.j.williams@intel.com
commit 085331dfc6bbe3501fb936e657331ca943827600
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@dwilli... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/vmx.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)
--- 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"
@@ -887,21 +888,18 @@ static const unsigned short vmcs_field_t
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)
Patches currently in stable-queue which might be from dan.j.williams@intel.com are
queue-4.14/x86kvm_Update_spectre-v1_mitigation.patch queue-4.14/x86_Introduce_barrier_nospec.patch queue-4.14/x86get_user_Use_pointer_masking_to_limit_speculation.patch queue-4.14/x86_Introduce___uaccess_begin_nospec()_and_uaccess_try_nospec.patch queue-4.14/x86paravirt_Remove_noreplace-paravirt_cmdline_option.patch queue-4.14/KVM_VMX_Make_indirect_call_speculation_safe.patch queue-4.14/KVMVMX_Allow_direct_access_to_MSR_IA32_SPEC_CTRL.patch queue-4.14/array_index_nospec_Sanitize_speculative_array_de-references.patch queue-4.14/Documentation_Document_array_index_nospec.patch queue-4.14/KVMSVM_Allow_direct_access_to_MSR_IA32_SPEC_CTRL.patch queue-4.14/KVMx86_Add_IBPB_support.patch queue-4.14/x86_Implement_array_index_mask_nospec.patch queue-4.14/KVMVMX_Emulate_MSR_IA32_ARCH_CAPABILITIES.patch queue-4.14/nl80211_Sanitize_array_index_in_parse_txq_params.patch queue-4.14/KVM_x86_Make_indirect_calls_in_emulator_speculation_safe.patch queue-4.14/x86uaccess_Use___uaccess_begin_nospec()_and_uaccess_try_nospec.patch queue-4.14/x86usercopy_Replace_open_coded_stacclac_with___uaccess_begin_end.patch queue-4.14/vfs_fdtable_Prevent_bounds-check_bypass_via_speculative_execution.patch queue-4.14/x86spectre_Report_get_user_mitigation_for_spectre_v1.patch queue-4.14/x86syscall_Sanitize_syscall_table_de-references_under_speculation.patch