Rick Edgecombe f2fde6a5bc KVM: VMX: Move RSB stuffing to before the first RET after VM-Exit ... The not-so-recent change to move VMX's VM-Exit handing to a dedicated "function" unintentionally exposed KVM to a speculative attack from the guest by executing a RET prior to stuffing the RSB. Make RSB stuffing happen immediately after VM-Exit, before any unpaired returns. Alternatively, the VM-Exit path could postpone full RSB stuffing until its current location by stuffing the RSB only as needed, or by avoiding returns in the VM-Exit path entirely, but both alternatives are beyond ugly since vmx_vmexit() has multiple indirect callers (by way of vmx_vmenter()). And putting the RSB stuffing immediately after VM-Exit makes it much less likely to be re-broken in the future. Note, the cost of PUSH/POP could be avoided in the normal flow by pairing the PUSH RAX with the POP RAX in __vmx_vcpu_run() and adding an a POP to nested_vmx_check_vmentry_hw(), but such a weird/subtle dependency is likely to cause problems in the long run, and PUSH/POP will take all of a few cycles, which is peanuts compared to the number of cycles required to fill the RSB. Fixes: 453eafbe65 ("KVM: VMX: Move VM-Enter + VM-Exit handling to non-inline sub-routines") Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@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: Paolo Bonzini <pbonzini@redhat.com>		2019-04-27 09:48:52 +02:00
..
capabilities.h
evmcs.c	x86/kvm/hyper-v: nested_enable_evmcs() sets vmcs_version incorrectly	2019-01-25 19:11:37 +01:00
evmcs.h
nested.c	KVM: nVMX: always use early vmcs check when EPT is disabled	2019-04-16 15:37:12 +02:00
nested.h
ops.h
pmu_intel.c
vmcs12.c
vmcs12.h
vmcs_shadow_fields.h
vmcs.h	KVM: nVMX: Cache host_rsp on a per-VMCS basis	2019-02-12 13:12:22 +01:00
vmenter.S	KVM: VMX: Move RSB stuffing to before the first RET after VM-Exit	2019-04-27 09:48:52 +02:00
vmx.c	KVM: VMX: Move RSB stuffing to before the first RET after VM-Exit	2019-04-27 09:48:52 +02:00
vmx.h	KVM: nVMX: allow tests to use bad virtual-APIC page address	2019-04-16 10:59:07 +02:00