From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Jim Mattson <jmattson@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>
Subject: [PATCH v4 17/24] KVM: nVMX: Add a helper to identify low-priority #DB traps
Date: Sat, 23 Jul 2022 00:51:30 +0000 [thread overview]
Message-ID: <20220723005137.1649592-18-seanjc@google.com> (raw)
In-Reply-To: <20220723005137.1649592-1-seanjc@google.com>
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
---
arch/x86/kvm/vmx/nested.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 361c788a73d5..379a7b647ac7 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3866,14 +3866,24 @@ 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;
}
/*
@@ -3885,8 +3895,9 @@ 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);
}
@@ -3956,7 +3967,7 @@ 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))
--
2.37.1.359.gd136c6c3e2-goog
next prev parent reply other threads:[~2022-07-23 0:53 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-23 0:51 [PATCH v4 00/24] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 01/24] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit" Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 02/24] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-08-01 16:00 ` Maxim Levitsky
2022-07-23 0:51 ` [PATCH v4 03/24] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 04/24] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 05/24] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 06/24] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 07/24] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 08/24] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 09/24] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 10/24] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 11/24] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 12/24] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-08-01 16:10 ` Maxim Levitsky
2022-07-23 0:51 ` [PATCH v4 13/24] KVM: x86: Formalize blocking of nested pending exceptions Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 14/24] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 15/24] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 16/24] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-07-23 0:51 ` Sean Christopherson [this message]
2022-07-23 0:51 ` [PATCH v4 18/24] KVM: nVMX: Document priority of all known events on Intel CPUs Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 19/24] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 20/24] KVM: x86: Treat pending TRIPLE_FAULT requests as pending exceptions Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 21/24] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 22/24] KVM: x86: Rename inject_pending_events() to kvm_check_and_inject_events() Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 23/24] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-07-23 0:51 ` [PATCH v4 24/24] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
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