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Date: Mon, 16 Nov 2020 10:26:14 -0800 From: isaku.yamahata@...el.com To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "H . Peter Anvin" <hpa@...or.com>, Paolo Bonzini <pbonzini@...hat.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org>, x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org Cc: isaku.yamahata@...el.com, isaku.yamahata@...il.com, Sean Christopherson <sean.j.christopherson@...el.com> Subject: [RFC PATCH 29/67] KVM: x86: Add a switch_db_regs flag to handle TDX's auto-switched behavior From: Sean Christopherson <sean.j.christopherson@...el.com> 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@...el.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com> --- 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
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