| Message ID | 20240209220752.388160-3-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Cleanup kvm_get_dr() usage | expand |
On 09.02.24 23:07, Sean Christopherson wrote: > Bite the bullet, and open code all direct reads of DR6 and DR7. KVM > currently has a mix of open coded accesses and calls to kvm_get_dr(), > which is confusing and ugly because there's no rhyme or reason as to why > any particular chunk of code uses kvm_get_dr(). > > The obvious alternative is to force all accesses through kvm_get_dr(), > but it's not at all clear that doing so would be a net positive, e.g. even > if KVM ends up wanting/needing to force all reads through a common helper, > e.g. to play caching games, the cost of reverting this change is likely > lower than the ongoing cost of maintaining weird, arbitrary code. > > No functional change intended. > > Cc: Mathias Krause <minipli@grsecurity.net> > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/smm.c | 8 ++++---- > arch/x86/kvm/vmx/nested.c | 2 +- > arch/x86/kvm/x86.c | 2 +- > 3 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c > index 19a7a0a31953..d06d43d8d2aa 100644 > --- a/arch/x86/kvm/smm.c > +++ b/arch/x86/kvm/smm.c > @@ -194,8 +194,8 @@ static void enter_smm_save_state_32(struct kvm_vcpu *vcpu, > for (i = 0; i < 8; i++) > smram->gprs[i] = kvm_register_read_raw(vcpu, i); > > - smram->dr6 = (u32)kvm_get_dr(vcpu, 6); > - smram->dr7 = (u32)kvm_get_dr(vcpu, 7); > + smram->dr6 = (u32)vcpu->arch.dr6; > + smram->dr7 = (u32)vcpu->arch.dr7; > > enter_smm_save_seg_32(vcpu, &smram->tr, &smram->tr_sel, VCPU_SREG_TR); > enter_smm_save_seg_32(vcpu, &smram->ldtr, &smram->ldtr_sel, VCPU_SREG_LDTR); > @@ -236,8 +236,8 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, > smram->rip = kvm_rip_read(vcpu); > smram->rflags = kvm_get_rflags(vcpu); > > - smram->dr6 = kvm_get_dr(vcpu, 6); > - smram->dr7 = kvm_get_dr(vcpu, 7); > + smram->dr6 = vcpu->arch.dr6; > + smram->dr7 = vcpu->arch.dr7; > > smram->cr0 = kvm_read_cr0(vcpu); > smram->cr3 = kvm_read_cr3(vcpu); > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 28d1088a1770..d05ddf751491 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -4433,7 +4433,7 @@ static void sync_vmcs02_to_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) > (vm_entry_controls_get(to_vmx(vcpu)) & VM_ENTRY_IA32E_MODE); > > if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_DEBUG_CONTROLS) > - vmcs12->guest_dr7 = kvm_get_dr(vcpu, 7); > + vmcs12->guest_dr7 = vcpu->arch.dr7; > > if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_IA32_EFER) > vmcs12->guest_ia32_efer = vcpu->arch.efer; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index bfffc13f91e6..5a08d895bde6 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5510,7 +5510,7 @@ static void kvm_vcpu_ioctl_x86_get_debugregs(struct kvm_vcpu *vcpu, > for (i = 0; i < ARRAY_SIZE(vcpu->arch.db); i++) > dbgregs->db[i] = vcpu->arch.db[i]; > > - dbgregs->dr6 = kvm_get_dr(vcpu, 6); > + dbgregs->dr6 = vcpu->arch.dr6; > dbgregs->dr7 = vcpu->arch.dr7; > } > Reviewed-by: Mathias Krause <minipli@grsecurity.net> Nice cleanup. Thanks a lot, Sean!
diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c index 19a7a0a31953..d06d43d8d2aa 100644 --- a/arch/x86/kvm/smm.c +++ b/arch/x86/kvm/smm.c @@ -194,8 +194,8 @@ static void enter_smm_save_state_32(struct kvm_vcpu *vcpu, for (i = 0; i < 8; i++) smram->gprs[i] = kvm_register_read_raw(vcpu, i); - smram->dr6 = (u32)kvm_get_dr(vcpu, 6); - smram->dr7 = (u32)kvm_get_dr(vcpu, 7); + smram->dr6 = (u32)vcpu->arch.dr6; + smram->dr7 = (u32)vcpu->arch.dr7; enter_smm_save_seg_32(vcpu, &smram->tr, &smram->tr_sel, VCPU_SREG_TR); enter_smm_save_seg_32(vcpu, &smram->ldtr, &smram->ldtr_sel, VCPU_SREG_LDTR); @@ -236,8 +236,8 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, smram->rip = kvm_rip_read(vcpu); smram->rflags = kvm_get_rflags(vcpu); - smram->dr6 = kvm_get_dr(vcpu, 6); - smram->dr7 = kvm_get_dr(vcpu, 7); + smram->dr6 = vcpu->arch.dr6; + smram->dr7 = vcpu->arch.dr7; smram->cr0 = kvm_read_cr0(vcpu); smram->cr3 = kvm_read_cr3(vcpu); diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 28d1088a1770..d05ddf751491 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4433,7 +4433,7 @@ static void sync_vmcs02_to_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) (vm_entry_controls_get(to_vmx(vcpu)) & VM_ENTRY_IA32E_MODE); if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_DEBUG_CONTROLS) - vmcs12->guest_dr7 = kvm_get_dr(vcpu, 7); + vmcs12->guest_dr7 = vcpu->arch.dr7; if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_IA32_EFER) vmcs12->guest_ia32_efer = vcpu->arch.efer; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bfffc13f91e6..5a08d895bde6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5510,7 +5510,7 @@ static void kvm_vcpu_ioctl_x86_get_debugregs(struct kvm_vcpu *vcpu, for (i = 0; i < ARRAY_SIZE(vcpu->arch.db); i++) dbgregs->db[i] = vcpu->arch.db[i]; - dbgregs->dr6 = kvm_get_dr(vcpu, 6); + dbgregs->dr6 = vcpu->arch.dr6; dbgregs->dr7 = vcpu->arch.dr7; }
Bite the bullet, and open code all direct reads of DR6 and DR7. KVM currently has a mix of open coded accesses and calls to kvm_get_dr(), which is confusing and ugly because there's no rhyme or reason as to why any particular chunk of code uses kvm_get_dr(). The obvious alternative is to force all accesses through kvm_get_dr(), but it's not at all clear that doing so would be a net positive, e.g. even if KVM ends up wanting/needing to force all reads through a common helper, e.g. to play caching games, the cost of reverting this change is likely lower than the ongoing cost of maintaining weird, arbitrary code. No functional change intended. Cc: Mathias Krause <minipli@grsecurity.net> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/smm.c | 8 ++++---- arch/x86/kvm/vmx/nested.c | 2 +- arch/x86/kvm/x86.c | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-)