Commit 2b384165 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: nVMX: Add a helper to identify low-priority #DB traps 



Add a helper to identify "low"-priority #DB traps, i.e. trap-like #DBs
that aren't TSS T flag #DBs, and tweak the related code to operate on any
queued exception.  A future commit will separate exceptions that are
intercepted by L1, i.e. cause nested VM-Exit, from those that do NOT
trigger nested VM-Exit.  I.e. there will be multiple exception structs
and multiple invocations of the helpers.

No functional change intended.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20220830231614.3580124-20-seanjc@google.com


Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 28360f88

arch/x86/kvm/vmx/nested.c

+17 −6
Original line number Diff line number Diff line
@@ -3912,14 +3912,24 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu, 
 * from the emulator (because such #DBs are fault-like and thus don't trigger

 * actions that fire on instruction retire).

 */

static inline unsigned long vmx_get_pending_dbg_trap(struct kvm_vcpu *vcpu)

static unsigned long vmx_get_pending_dbg_trap(struct kvm_queued_exception *ex)

{

	if (!vcpu->arch.exception.pending ||

	    vcpu->arch.exception.vector != DB_VECTOR)

	if (!ex->pending || ex->vector != DB_VECTOR)

		return 0;



	/* General Detect #DBs are always fault-like. */

	return vcpu->arch.exception.payload & ~DR6_BD;

	return ex->payload & ~DR6_BD;

}



/*

 * Returns true if there's a pending #DB exception that is lower priority than

 * a pending Monitor Trap Flag VM-Exit.  TSS T-flag #DBs are not emulated by

 * KVM, but could theoretically be injected by userspace.  Note, this code is

 * imperfect, see above.

 */

static bool vmx_is_low_priority_db_trap(struct kvm_queued_exception *ex)

{

	return vmx_get_pending_dbg_trap(ex) & ~DR6_BT;

}



/*
@@ -3931,8 +3941,9 @@ static inline unsigned long vmx_get_pending_dbg_trap(struct kvm_vcpu *vcpu) 
 */

static void nested_vmx_update_pending_dbg(struct kvm_vcpu *vcpu)

{

	unsigned long pending_dbg = vmx_get_pending_dbg_trap(vcpu);

	unsigned long pending_dbg;



	pending_dbg = vmx_get_pending_dbg_trap(&vcpu->arch.exception);

	if (pending_dbg)

		vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS, pending_dbg);

}
@@ -4002,7 +4013,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu) 
	 * prioritize SMI over MTF and trap-like #DBs.

	 */

	if (vcpu->arch.exception.pending &&

	    !(vmx_get_pending_dbg_trap(vcpu) & ~DR6_BT)) {

	    !vmx_is_low_priority_db_trap(&vcpu->arch.exception)) {

		if (block_nested_exceptions)

			return -EBUSY;

		if (!nested_vmx_check_exception(vcpu, &exit_qual))