diff options
| author | Paolo Bonzini | 2021-08-10 06:07:06 -0400 |
|---|---|---|
| committer | Paolo Bonzini | 2021-08-13 03:35:14 -0400 |
| commit | 375e28ffc0cf4fc48862c03994ec4a93254cf1c6 (patch) | |
| tree | d287cf8d58a7f66455f89a67a102abb6e41cff62 | |
| parent | 34e9f860071f717965f1816171a11eaf2d378ee0 (diff) | |
KVM: X86: Set host DR6 only on VMX and for KVM_DEBUGREG_WONT_EXIT
Commit c77fb5fe6f03 ("KVM: x86: Allow the guest to run with dirty debug
registers") allows the guest accessing to DRs without exiting when
KVM_DEBUGREG_WONT_EXIT and we need to ensure that they are synchronized
on entry to the guest---including DR6 that was not synced before the commit.
But the commit sets the hardware DR6 not only when KVM_DEBUGREG_WONT_EXIT,
but also when KVM_DEBUGREG_BP_ENABLED. The second case is unnecessary
and just leads to a more case which leaks stale DR6 to the host which has
to be resolved by unconditionally reseting DR6 in kvm_arch_vcpu_put().
Even if KVM_DEBUGREG_WONT_EXIT, however, setting the host DR6 only matters
on VMX because SVM always uses the DR6 value from the VMCB. So move this
line to vmx.c and make it conditional on KVM_DEBUGREG_WONT_EXIT.
Reported-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 1 |
2 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index ae8e62df16dd..7c1c8ef1a286 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6625,6 +6625,10 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu) vmx->loaded_vmcs->host_state.cr4 = cr4; } + /* When KVM_DEBUGREG_WONT_EXIT, dr6 is accessible in guest. */ + if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) + set_debugreg(vcpu->arch.dr6, 6); + /* When single-stepping over STI and MOV SS, we must clear the * corresponding interruptibility bits in the guest state. Otherwise * vmentry fails as it then expects bit 14 (BS) in pending debug diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index eca5f005a7fc..15ac8645e532 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9602,7 +9602,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) set_debugreg(vcpu->arch.eff_db[1], 1); set_debugreg(vcpu->arch.eff_db[2], 2); set_debugreg(vcpu->arch.eff_db[3], 3); - set_debugreg(vcpu->arch.dr6, 6); } else if (unlikely(hw_breakpoint_active())) { set_debugreg(0, 7); } |