KVM: x86: Open code all direct reads to guest DR6 and 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>
Reviewed-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20240209220752.388160-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c
index 19a7a0a31953734b224927eea945b027f1738776..d06d43d8d2aa462e4f789b5ae31c4d6d36031cb3 100644 (file)
--- 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 692fd559f0864457b01c7bfc07c8123a2ac4c38e..0cd977f22c4b78b69e1b5c3f182ba6e0f2e14d01 100644 (file)
--- 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 b195eb21639cee40e2cebc33ec2d1091eb1e04ed..f97e443ce85356ff52512496a4dd473d778e229b 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5514,7 +5514,7 @@ 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;
 }