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KVM: x86: Open code all direct reads to guest DR6 and DR7

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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>
This commit is contained in:
Sean Christopherson 2024-02-09 14:07:52 -08:00
parent fc5375dd8c
commit 2a5f091ce1
3 changed files with 6 additions and 6 deletions
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8
arch/x86/kvm/smm.c
View File

@ -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);

2
arch/x86/kvm/vmx/nested.c
View File

@ -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;

2
arch/x86/kvm/x86.c
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@ -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;
}