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Subject[PATCH v2 2/2] KVM: x86: move kvm_inject_gp up from kvm_set_dr to callers
Date
Push the injection of #GP up to the callers, since they can just use
kvm_complete_insn_gp and __kvm_set_dr pretty much returns what the
callers can pass to kvm_complete_insn_gp.

Therefore, rename __kvm_set_dr to kvm_set_dr and drop the kvm_set_dr
wrapper. This also allows nested VMX code, which really wanted to use
__kvm_set_dr, to use the right function.

While at it, remove the kvm_require_dr() check from the SVM handler.
The APM states:

All normal exception checks take precedence over the SVM intercepts.

and that includes the CR4.DE=1 #UD.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/svm/svm.c | 13 +++++--------
arch/x86/kvm/vmx/vmx.c | 17 ++++++++++-------
arch/x86/kvm/x86.c | 19 +++++--------------
3 files changed, 20 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 4141caea857a..ea1bd96a9804 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2619,6 +2619,7 @@ static int dr_interception(struct vcpu_svm *svm)
{
int reg, dr;
unsigned long val;
+ int err = 0;

if (svm->vcpu.guest_debug == 0) {
/*
@@ -2636,20 +2637,16 @@ static int dr_interception(struct vcpu_svm *svm)

reg = svm->vmcb->control.exit_info_1 & SVM_EXITINFO_REG_MASK;
dr = svm->vmcb->control.exit_code - SVM_EXIT_READ_DR0;
-
if (dr >= 16) { /* mov to DRn */
- if (!kvm_require_dr(&svm->vcpu, dr - 16))
- return 1;
+ dr -= 16;
val = kvm_register_read(&svm->vcpu, reg);
- kvm_set_dr(&svm->vcpu, dr - 16, val);
+ err = kvm_set_dr(&svm->vcpu, dr, val);
} else {
- if (!kvm_require_dr(&svm->vcpu, dr))
- return 1;
kvm_get_dr(&svm->vcpu, dr, &val);
kvm_register_write(&svm->vcpu, reg, val);
}

- return kvm_skip_emulated_instruction(&svm->vcpu);
+ return kvm_complete_insn_gp(&svm->vcpu, err);
}

static int cr8_write_interception(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 049fbbd0aa1a..13898871e5b0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5095,6 +5095,7 @@ static int handle_dr(struct kvm_vcpu *vcpu)
{
unsigned long exit_qualification;
int dr, dr7, reg;
+ int err = 1;

exit_qualification = vmx_get_exit_qual(vcpu);
dr = exit_qualification & DEBUG_REG_ACCESS_NUM;
@@ -5103,9 +5104,9 @@ static int handle_dr(struct kvm_vcpu *vcpu)
if (!kvm_require_dr(vcpu, dr))
return 1;

- /* Do not handle if the CPL > 0, will trigger GP on re-entry */
- if (!kvm_require_cpl(vcpu, 0))
- return 1;
+ if (kvm_x86_ops.get_cpl(vcpu) > 0)
+ goto out;
+
dr7 = vmcs_readl(GUEST_DR7);
if (dr7 & DR7_GD) {
/*
@@ -5144,11 +5145,13 @@ static int handle_dr(struct kvm_vcpu *vcpu)

kvm_get_dr(vcpu, dr, &val);
kvm_register_write(vcpu, reg, val);
- } else
- if (kvm_set_dr(vcpu, dr, kvm_register_readl(vcpu, reg)))
- return 1;
+ err = 0;
+ } else {
+ err = kvm_set_dr(vcpu, dr, kvm_register_readl(vcpu, reg));
+ }

- return kvm_skip_emulated_instruction(vcpu);
+out:
+ return kvm_complete_insn_gp(vcpu, err);
}

static void vmx_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dcb67429b75d..baa90ae76ba5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1143,7 +1143,7 @@ static u64 kvm_dr6_fixed(struct kvm_vcpu *vcpu)
return fixed;
}

-static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
+int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
{
size_t size = ARRAY_SIZE(vcpu->arch.db);

@@ -1156,13 +1156,13 @@ static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
case 4:
case 6:
if (!kvm_dr6_valid(val))
- return -1; /* #GP */
+ return 1; /* #GP */
vcpu->arch.dr6 = (val & DR6_VOLATILE) | kvm_dr6_fixed(vcpu);
break;
case 5:
default: /* 7 */
if (!kvm_dr7_valid(val))
- return -1; /* #GP */
+ return 1; /* #GP */
vcpu->arch.dr7 = (val & DR7_VOLATILE) | DR7_FIXED_1;
kvm_update_dr7(vcpu);
break;
@@ -1170,15 +1170,6 @@ static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)

return 0;
}
-
-int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
-{
- if (__kvm_set_dr(vcpu, dr, val)) {
- kvm_inject_gp(vcpu, 0);
- return 1;
- }
- return 0;
-}
EXPORT_SYMBOL_GPL(kvm_set_dr);

void kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val)
@@ -6619,7 +6610,7 @@ static int emulator_set_dr(struct x86_emulate_ctxt *ctxt, int dr,
unsigned long value)
{

- return __kvm_set_dr(emul_to_vcpu(ctxt), dr, value);
+ return kvm_set_dr(emul_to_vcpu(ctxt), dr, value);
}

static u64 mk_cr_64(u64 curr_cr, u32 new_val)
@@ -8664,7 +8655,7 @@ static void enter_smm(struct kvm_vcpu *vcpu)
dt.address = dt.size = 0;
static_call(kvm_x86_set_idt)(vcpu, &dt);

- __kvm_set_dr(vcpu, 7, DR7_FIXED_1);
+ kvm_set_dr(vcpu, 7, DR7_FIXED_1);

cs.selector = (vcpu->arch.smbase >> 4) & 0xffff;
cs.base = vcpu->arch.smbase;
--
2.26.2
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