AuxXxilium/linux_dsm_epyc7002
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0e0ab73c9a
linux_dsm_epyc7002/arch/x86/kvm/vmx
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Sean Christopherson 0e0ab73c9a 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: 0cb5b30698 ("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>
2019-02-12 13:12:14 +01:00
..
capabilities.h KVM: x86: Add Intel PT virtualization work mode 2018-12-21 11:28:34 +01:00
evmcs.c x86/kvm/hyper-v: nested_enable_evmcs() sets vmcs_version incorrectly 2019-01-25 19:11:37 +01:00
evmcs.h x86/kvm/hyper-v: Introduce nested_get_evmcs_version() helper 2018-12-14 17:59:54 +01:00
nested.c KVM: nVMX: Check a single byte for VMCS "launched" in nested early checks 2019-02-12 13:12:13 +01:00
nested.h KVM: nVMX: Move nested code to dedicated files 2018-12-14 17:59:46 +01:00
ops.h KVM: VMX: Move VMX instruction wrappers to a dedicated header file 2018-12-14 17:17:27 +01:00
pmu_intel.c
vmcs12.c KVM: nVMX: Move vmcs12 code to dedicated files 2018-12-14 12:34:30 +01:00
vmcs12.h KVM: nVMX: Move vmcs12 code to dedicated files 2018-12-14 12:34:30 +01:00
vmcs_shadow_fields.h
vmcs.h KVM: VMX: Move eVMCS code to dedicated files 2018-12-14 14:00:06 +01:00
vmenter.S KVM: VMX: Move VM-Enter + VM-Exit handling to non-inline sub-routines 2018-12-21 12:02:50 +01:00
vmx.c KVM: VMX: Zero out *all* general purpose registers after VM-Exit 2019-02-12 13:12:14 +01:00
vmx.h KVM: VMX: Move VM-Enter + VM-Exit handling to non-inline sub-routines 2018-12-21 12:02:50 +01:00