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KVM: x86: Set guest DR6 by kvm_queue_exception_p() in instruction emulation

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Record DR6 in emulate_db() and use kvm_queue_exception_p() to set DR6
instead of directly using kvm_set_dr6() in emulation, i.e. rely on the
standard exception path to set DR6 via kvm_deliver_exception_payload().
This keeps the handling of DR6 during #DB injection consistent with other
code paths.

No functional change intended.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
[sean: fix e vs. p goof, add kvm_inject_emulated_db() right away]
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260515222638.1949982-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Hou Wenlong 2026-05-15 15:26:31 -07:00 committed by Sean Christopherson
parent 17afe9b750
commit dfc1c4687e
3 changed files with 18 additions and 12 deletions
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14
arch/x86/kvm/emulate.c
View File

@ -540,8 +540,9 @@ static int emulate_exception(struct x86_emulate_ctxt *ctxt, int vec,
return X86EMUL_PROPAGATE_FAULT;
}
static int emulate_db(struct x86_emulate_ctxt *ctxt)
static int emulate_db(struct x86_emulate_ctxt *ctxt, unsigned long dr6)
{
ctxt->exception.dr6 = dr6;
return emulate_exception(ctxt, DB_VECTOR, 0, false);
}
@ -3847,15 +3848,8 @@ static int check_dr_read(struct x86_emulate_ctxt *ctxt)
if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5))
return emulate_ud(ctxt);
if (ctxt->ops->get_dr(ctxt, 7) & DR7_GD) {
ulong dr6;
dr6 = ctxt->ops->get_dr(ctxt, 6);
dr6 &= ~DR_TRAP_BITS;
dr6 |= DR6_BD | DR6_ACTIVE_LOW;
ctxt->ops->set_dr(ctxt, 6, dr6);
return emulate_db(ctxt);
}
if (ctxt->ops->get_dr(ctxt, 7) & DR7_GD)
return emulate_db(ctxt, DR6_BD);
return X86EMUL_CONTINUE;
}

6
arch/x86/kvm/kvm_emulate.h
View File

@ -24,7 +24,11 @@ struct x86_exception {
bool error_code_valid;
u16 error_code;
bool nested_page_fault;
u64 address; /* cr2 or nested page fault gpa */
union {
u64 address; /* cr2 or nested page fault gpa */
unsigned long dr6;
u64 payload;
};
u8 async_page_fault;
unsigned long exit_qualification;
};

10
arch/x86/kvm/x86.c
View File

@ -8977,11 +8977,18 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
}
}
static void kvm_inject_emulated_db(struct kvm_vcpu *vcpu, unsigned long dr6)
{
kvm_queue_exception_p(vcpu, DB_VECTOR, dr6);
}
static void inject_emulated_exception(struct kvm_vcpu *vcpu)
{
struct x86_exception *ex = &vcpu->arch.emulate_ctxt->exception;
if (ex->vector == PF_VECTOR)
if (ex->vector == DB_VECTOR)
kvm_inject_emulated_db(vcpu, ex->dr6);
else if (ex->vector == PF_VECTOR)
kvm_inject_emulated_page_fault(vcpu, ex);
else if (ex->error_code_valid)
kvm_queue_exception_e(vcpu, ex->vector, ex->error_code);
@ -9026,6 +9033,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
ctxt->interruptibility = 0;
ctxt->have_exception = false;
ctxt->exception.vector = -1;
ctxt->exception.payload = 0;
ctxt->perm_ok = false;
init_decode_cache(ctxt);