From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Add a flag, KVM_DEBUGREG_AUTO_SWITCHED, to skip saving/restoring DRs
irrespective of any other flags. TDX-SEAM unconditionally saves and
restores host DRs, ergo there is nothing to do.
Opportunistically convert the KVM_DEBUGREG_* definitions to use BIT().
Reported-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 7 ++++---
arch/x86/kvm/x86.c | 6 ++++--
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a6c89666ec49..815469875445 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -464,9 +464,10 @@ struct kvm_pmu {
struct kvm_pmu_ops;
enum {
- KVM_DEBUGREG_BP_ENABLED = 1,
- KVM_DEBUGREG_WONT_EXIT = 2,
- KVM_DEBUGREG_RELOAD = 4,
+ KVM_DEBUGREG_BP_ENABLED = BIT(0),
+ KVM_DEBUGREG_WONT_EXIT = BIT(1),
+ KVM_DEBUGREG_RELOAD = BIT(2),
+ KVM_DEBUGREG_AUTO_SWITCHED = BIT(3),
};
struct kvm_mtrr_range {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 42bd24ba7fdd..098888edc3ad 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9009,7 +9009,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (test_thread_flag(TIF_NEED_FPU_LOAD))
switch_fpu_return();
- if (unlikely(vcpu->arch.switch_db_regs)) {
+ if (unlikely(vcpu->arch.switch_db_regs & ~KVM_DEBUGREG_AUTO_SWITCHED)) {
set_debugreg(0, 7);
set_debugreg(vcpu->arch.eff_db[0], 0);
set_debugreg(vcpu->arch.eff_db[1], 1);
@@ -9029,6 +9029,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
*/
if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) {
WARN_ON(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP);
+ WARN_ON(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCHED);
kvm_x86_ops.sync_dirty_debug_regs(vcpu);
kvm_update_dr0123(vcpu);
kvm_update_dr7(vcpu);
@@ -9042,7 +9043,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
* care about the messed up debug address registers. But if
* we have some of them active, restore the old state.
*/
- if (hw_breakpoint_active())
+ if (hw_breakpoint_active() &&
+ !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCHED))
hw_breakpoint_restore();
vcpu->arch.last_vmentry_cpu = vcpu->cpu;
--
2.17.1
