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author | Sean Christopherson <sean.j.christopherson@intel.com> | 2019-01-25 07:40:50 -0800 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-02-12 13:12:14 +0100 |
commit | 0e0ab73c9a0243736bcd779b30b717e23ba9a56d (patch) | |
tree | d63f7f520fc0d8f338ea4b55c6bcc032a407cf26 /drivers/rtc/rtc-ds3232.c | |
parent | 1ce072cbfd8dba46f117804850398e0b3040a541 (diff) |
KVM: VMX: Zero out *all* general purpose registers after VM-Exit
...except RSP, which is restored by hardware as part of VM-Exit.
Paolo theorized that restoring registers from the stack after a VM-Exit
in lieu of zeroing them could lead to speculative execution with the
guest's values, e.g. if the stack accesses miss the L1 cache[1].
Zeroing XORs are dirt cheap, so just be ultra-paranoid.
Note that the scratch register (currently RCX) used to save/restore the
guest state is also zeroed as its host-defined value is loaded via the
stack, just with a MOV instead of a POP.
[1] https://patchwork.kernel.org/patch/10771539/#22441255
Fixes: 0cb5b30698fd ("kvm: vmx: Scrub hardware GPRs at VM-exit")
Cc: <stable@vger.kernel.org>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'drivers/rtc/rtc-ds3232.c')
0 files changed, 0 insertions, 0 deletions