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KVM: nVMX: Add a helper to identify low-priority #DB traps

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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: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20220830231614.3580124-20-seanjc@google.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-08-30 23:16:06 +00:00 committed by Paolo Bonzini
parent 28360f8870
commit 2b384165f4
1 changed files with 17 additions and 6 deletions
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23
arch/x86/kvm/vmx/nested.c
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@ -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))