Make get_dr6() and set_dr6() optional and drop the VMX implementations,
which are for all intents and purposes nops. This avoids a retpoline on
VMX when reading/writing DR6, at minimal cost (~1 uop) to SVM.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 11 -----------
arch/x86/kvm/x86.c | 6 ++++--
2 files changed, 4 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index de18cd386bb1..e157bdc218ea 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5008,15 +5008,6 @@ static int handle_dr(struct kvm_vcpu *vcpu)
return kvm_skip_emulated_instruction(vcpu);
}
-static u64 vmx_get_dr6(struct kvm_vcpu *vcpu)
-{
- return vcpu->arch.dr6;
-}
-
-static void vmx_set_dr6(struct kvm_vcpu *vcpu, unsigned long val)
-{
-}
-
static void vmx_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)
{
get_debugreg(vcpu->arch.db[0], 0);
@@ -7799,8 +7790,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
.set_idt = vmx_set_idt,
.get_gdt = vmx_get_gdt,
.set_gdt = vmx_set_gdt,
- .get_dr6 = vmx_get_dr6,
- .set_dr6 = vmx_set_dr6,
.set_dr7 = vmx_set_dr7,
.sync_dirty_debug_regs = vmx_sync_dirty_debug_regs,
.cache_reg = vmx_cache_reg,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8ec356ac1e6e..eccbfcb6a4e5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1069,7 +1069,8 @@ static void kvm_update_dr0123(struct kvm_vcpu *vcpu)
static void kvm_update_dr6(struct kvm_vcpu *vcpu)
{
- if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP))
+ if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) &&
+ kvm_x86_ops.set_dr6)
kvm_x86_ops.set_dr6(vcpu, vcpu->arch.dr6);
}
@@ -1148,7 +1149,8 @@ int kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val)
case 4:
/* fall through */
case 6:
- if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
+ if ((vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) ||
+ !kvm_x86_ops.get_dr6)
*val = vcpu->arch.dr6;
else
*val = kvm_x86_ops.get_dr6(vcpu);
--
2.26.0
