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Message-Id: <20200421075328.14458-3-sean.j.christopherson@intel.com>
Date: Tue, 21 Apr 2020 00:53:28 -0700
From: Sean Christopherson <sean.j.christopherson@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <sean.j.christopherson@...el.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH v3 2/2] KVM: VMX: Convert vcpu_vmx.exit_reason to a union
Convert vcpu_vmx.exit_reason from a u32 to a union (of size u32). The
full VM_EXIT_REASON field is comprised of a 16-bit basic exit reason in
bits 15:0, and single-bit modifiers in bits 31:16.
Historically, KVM has only had to worry about handling the "failed
VM-Entry" modifier, which could only be set in very specific flows and
required dedicated handling. I.e. manually stripping the FAILED_VMENTRY
bit was a somewhat viable approach. But even with only a single bit to
worry about, KVM has had several bugs related to comparing a basic exit
reason against the full exit reason store in vcpu_vmx.
Upcoming Intel features, e.g. SGX, will add new modifier bits that can
be set on more or less any VM-Exit, as opposed to the significantly more
restricted FAILED_VMENTRY, i.e. correctly handling everything in one-off
flows isn't scalable. Tracking exit reason in a union forces code to
explicitly choose between consuming the full exit reason and the basic
exit, and is a convenient way to document and access the modifiers.
No functional change intended.
Cc: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
arch/x86/kvm/vmx/nested.c | 37 ++++++++++++++--------
arch/x86/kvm/vmx/vmx.c | 65 ++++++++++++++++++++-------------------
arch/x86/kvm/vmx/vmx.h | 25 ++++++++++++++-
3 files changed, 82 insertions(+), 45 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 995c319cc7ad..dd41735dc1b0 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3247,7 +3247,10 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
bool evaluate_pending_interrupts;
- u32 exit_reason = EXIT_REASON_INVALID_STATE;
+ union vmx_exit_reason exit_reason = {
+ .basic = EXIT_REASON_INVALID_STATE,
+ .failed_vmentry = 1,
+ };
u32 exit_qual;
if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu))
@@ -3308,7 +3311,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
goto vmentry_fail_vmexit_guest_mode;
if (from_vmentry) {
- exit_reason = EXIT_REASON_MSR_LOAD_FAIL;
+ exit_reason.basic = EXIT_REASON_MSR_LOAD_FAIL;
exit_qual = nested_vmx_load_msr(vcpu,
vmcs12->vm_entry_msr_load_addr,
vmcs12->vm_entry_msr_load_count);
@@ -3376,7 +3379,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
return NVMX_VMENTRY_VMEXIT;
load_vmcs12_host_state(vcpu, vmcs12);
- vmcs12->vm_exit_reason = exit_reason | VMX_EXIT_REASONS_FAILED_VMENTRY;
+ vmcs12->vm_exit_reason = exit_reason.full;
vmcs12->exit_qualification = exit_qual;
if (enable_shadow_vmcs || vmx->nested.hv_evmcs)
vmx->nested.need_vmcs12_to_shadow_sync = true;
@@ -5410,7 +5413,12 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu)
return kvm_skip_emulated_instruction(vcpu);
fail:
- nested_vmx_vmexit(vcpu, vmx->exit_reason,
+ /*
+ * This is effectively a reflected VM-Exit, as opposed to a synthesized
+ * nested VM-Exit. Pass the original exit reason, i.e. don't hardcode
+ * EXIT_REASON_VMFUNC as the exit reason.
+ */
+ nested_vmx_vmexit(vcpu, vmx->exit_reason.full,
vmx_get_intr_info(vcpu),
vmx_get_exit_qual(vcpu));
return 1;
@@ -5478,7 +5486,8 @@ static bool nested_vmx_exit_handled_io(struct kvm_vcpu *vcpu,
* MSR bitmap. This may be the case even when L0 doesn't use MSR bitmaps.
*/
static bool nested_vmx_exit_handled_msr(struct kvm_vcpu *vcpu,
- struct vmcs12 *vmcs12, u32 exit_reason)
+ struct vmcs12 *vmcs12,
+ union vmx_exit_reason exit_reason)
{
u32 msr_index = kvm_rcx_read(vcpu);
gpa_t bitmap;
@@ -5492,7 +5501,7 @@ static bool nested_vmx_exit_handled_msr(struct kvm_vcpu *vcpu,
* First we need to figure out which of the four to use:
*/
bitmap = vmcs12->msr_bitmap;
- if (exit_reason == EXIT_REASON_MSR_WRITE)
+ if (exit_reason.basic == EXIT_REASON_MSR_WRITE)
bitmap += 2048;
if (msr_index >= 0xc0000000) {
msr_index -= 0xc0000000;
@@ -5629,11 +5638,12 @@ static bool nested_vmx_exit_handled_mtf(struct vmcs12 *vmcs12)
* Return true if L0 wants to handle an exit from L2 regardless of whether or not
* L1 wants the exit. Only call this when in is_guest_mode (L2).
*/
-static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu, u32 exit_reason)
+static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu,
+ union vmx_exit_reason exit_reason)
{
u32 intr_info;
- switch (exit_reason) {
+ switch (exit_reason.basic) {
case EXIT_REASON_EXCEPTION_NMI:
intr_info = vmx_get_intr_info(vcpu);
if (is_nmi(intr_info))
@@ -5689,12 +5699,13 @@ static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu, u32 exit_reason)
* Return 1 if L1 wants to intercept an exit from L2. Only call this when in
* is_guest_mode (L2).
*/
-static bool nested_vmx_l1_wants_exit(struct kvm_vcpu *vcpu, u32 exit_reason)
+static bool nested_vmx_l1_wants_exit(struct kvm_vcpu *vcpu,
+ union vmx_exit_reason exit_reason)
{
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
u32 intr_info;
- switch (exit_reason) {
+ switch (exit_reason.basic) {
case EXIT_REASON_EXCEPTION_NMI:
intr_info = vmx_get_intr_info(vcpu);
if (is_nmi(intr_info))
@@ -5813,7 +5824,7 @@ static bool nested_vmx_l1_wants_exit(struct kvm_vcpu *vcpu, u32 exit_reason)
bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u32 exit_reason = vmx->exit_reason;
+ union vmx_exit_reason exit_reason = vmx->exit_reason;
u32 exit_intr_info, exit_qual;
WARN_ON_ONCE(vmx->nested.nested_run_pending);
@@ -5834,7 +5845,7 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
exit_intr_info = vmx_get_intr_info(vcpu);
exit_qual = vmx_get_exit_qual(vcpu);
- trace_kvm_nested_vmexit(kvm_rip_read(vcpu), exit_reason, exit_qual,
+ trace_kvm_nested_vmexit(kvm_rip_read(vcpu), exit_reason.full, exit_qual,
vmx->idt_vectoring_info, exit_intr_info,
vmcs_read32(VM_EXIT_INTR_ERROR_CODE),
KVM_ISA_VMX);
@@ -5863,7 +5874,7 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
}
reflect_vmexit:
- nested_vmx_vmexit(vcpu, exit_reason, exit_intr_info, exit_qual);
+ nested_vmx_vmexit(vcpu, exit_reason.full, exit_intr_info, exit_qual);
return true;
}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 766303b31949..28035c77a03c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1567,7 +1567,7 @@ static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
* i.e. we end up advancing IP with some random value.
*/
if (!static_cpu_has(X86_FEATURE_HYPERVISOR) ||
- to_vmx(vcpu)->exit_reason != EXIT_REASON_EPT_MISCONFIG) {
+ to_vmx(vcpu)->exit_reason.basic != EXIT_REASON_EPT_MISCONFIG) {
rip = kvm_rip_read(vcpu);
rip += vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
kvm_rip_write(vcpu, rip);
@@ -5869,10 +5869,11 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu,
enum exit_fastpath_completion exit_fastpath)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u32 exit_reason = vmx->exit_reason;
+ union vmx_exit_reason exit_reason = vmx->exit_reason;
u32 vectoring_info = vmx->idt_vectoring_info;
+ u16 exit_handler_index;
- trace_kvm_exit(exit_reason, vcpu, KVM_ISA_VMX);
+ trace_kvm_exit(exit_reason.full, vcpu, KVM_ISA_VMX);
/*
* Flush logged GPAs PML buffer, this will make dirty_bitmap more
@@ -5906,11 +5907,11 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu,
return 1;
}
- if (exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY) {
+ if (exit_reason.failed_vmentry) {
dump_vmcs();
vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY;
vcpu->run->fail_entry.hardware_entry_failure_reason
- = exit_reason;
+ = exit_reason.full;
return 0;
}
@@ -5930,17 +5931,17 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu,
* will cause infinite loop.
*/
if ((vectoring_info & VECTORING_INFO_VALID_MASK) &&
- (exit_reason != EXIT_REASON_EXCEPTION_NMI &&
- exit_reason != EXIT_REASON_EPT_VIOLATION &&
- exit_reason != EXIT_REASON_PML_FULL &&
- exit_reason != EXIT_REASON_TASK_SWITCH)) {
+ (exit_reason.basic != EXIT_REASON_EXCEPTION_NMI &&
+ exit_reason.basic != EXIT_REASON_EPT_VIOLATION &&
+ exit_reason.basic != EXIT_REASON_PML_FULL &&
+ exit_reason.basic != EXIT_REASON_TASK_SWITCH)) {
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV;
vcpu->run->internal.ndata = 3;
vcpu->run->internal.data[0] = vectoring_info;
- vcpu->run->internal.data[1] = exit_reason;
+ vcpu->run->internal.data[1] = exit_reason.full;
vcpu->run->internal.data[2] = vcpu->arch.exit_qualification;
- if (exit_reason == EXIT_REASON_EPT_MISCONFIG) {
+ if (exit_reason.basic == EXIT_REASON_EPT_MISCONFIG) {
vcpu->run->internal.ndata++;
vcpu->run->internal.data[3] =
vmcs_read64(GUEST_PHYSICAL_ADDRESS);
@@ -5972,38 +5973,39 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu,
return 1;
}
- if (exit_reason >= kvm_vmx_max_exit_handlers)
+ if (exit_reason.basic >= kvm_vmx_max_exit_handlers)
goto unexpected_vmexit;
#ifdef CONFIG_RETPOLINE
- if (exit_reason == EXIT_REASON_MSR_WRITE)
+ if (exit_reason.basic == EXIT_REASON_MSR_WRITE)
return kvm_emulate_wrmsr(vcpu);
- else if (exit_reason == EXIT_REASON_PREEMPTION_TIMER)
+ else if (exit_reason.basic == EXIT_REASON_PREEMPTION_TIMER)
return handle_preemption_timer(vcpu);
- else if (exit_reason == EXIT_REASON_INTERRUPT_WINDOW)
+ else if (exit_reason.basic == EXIT_REASON_INTERRUPT_WINDOW)
return handle_interrupt_window(vcpu);
- else if (exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
+ else if (exit_reason.basic == EXIT_REASON_EXTERNAL_INTERRUPT)
return handle_external_interrupt(vcpu);
- else if (exit_reason == EXIT_REASON_HLT)
+ else if (exit_reason.basic == EXIT_REASON_HLT)
return kvm_emulate_halt(vcpu);
- else if (exit_reason == EXIT_REASON_EPT_MISCONFIG)
+ else if (exit_reason.basic == EXIT_REASON_EPT_MISCONFIG)
return handle_ept_misconfig(vcpu);
#endif
- exit_reason = array_index_nospec(exit_reason,
- kvm_vmx_max_exit_handlers);
- if (!kvm_vmx_exit_handlers[exit_reason])
+ exit_handler_index = array_index_nospec((u16)exit_reason.basic,
+ kvm_vmx_max_exit_handlers);
+ if (!kvm_vmx_exit_handlers[exit_handler_index])
goto unexpected_vmexit;
- return kvm_vmx_exit_handlers[exit_reason](vcpu);
+ return kvm_vmx_exit_handlers[exit_handler_index](vcpu);
unexpected_vmexit:
- vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", exit_reason);
+ vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n",
+ exit_reason.full);
dump_vmcs();
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror =
KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
vcpu->run->internal.ndata = 1;
- vcpu->run->internal.data[0] = exit_reason;
+ vcpu->run->internal.data[0] = exit_reason.full;
return 0;
}
@@ -6354,9 +6356,9 @@ static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- if (vmx->exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
+ if (vmx->exit_reason.basic == EXIT_REASON_EXTERNAL_INTERRUPT)
handle_external_interrupt_irqoff(vcpu);
- else if (vmx->exit_reason == EXIT_REASON_EXCEPTION_NMI)
+ else if (vmx->exit_reason.basic == EXIT_REASON_EXCEPTION_NMI)
handle_exception_nmi_irqoff(vmx);
}
@@ -6722,18 +6724,19 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmx->idt_vectoring_info = 0;
if (unlikely(vmx->fail)) {
- vmx->exit_reason = 0xdead;
+ vmx->exit_reason.full = 0xdead;
return EXIT_FASTPATH_NONE;
}
- vmx->exit_reason = vmcs_read32(VM_EXIT_REASON);
- if (unlikely((u16)vmx->exit_reason == EXIT_REASON_MCE_DURING_VMENTRY))
+ vmx->exit_reason.full = vmcs_read32(VM_EXIT_REASON);
+ if (unlikely(vmx->exit_reason.basic == EXIT_REASON_MCE_DURING_VMENTRY))
kvm_machine_check();
- if (unlikely(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
+ if (unlikely(vmx->exit_reason.failed_vmentry))
return EXIT_FASTPATH_NONE;
- if (!is_guest_mode(vcpu) && vmx->exit_reason == EXIT_REASON_MSR_WRITE)
+ if (!is_guest_mode(vcpu) &&
+ vmx->exit_reason.basic == EXIT_REASON_MSR_WRITE)
exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
else
exit_fastpath = EXIT_FASTPATH_NONE;
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index edfb739e5907..ef1539cdb416 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -91,6 +91,29 @@ struct pt_desc {
struct pt_ctx guest;
};
+union vmx_exit_reason {
+ struct {
+ u32 basic : 16;
+ u32 reserved16 : 1;
+ u32 reserved17 : 1;
+ u32 reserved18 : 1;
+ u32 reserved19 : 1;
+ u32 reserved20 : 1;
+ u32 reserved21 : 1;
+ u32 reserved22 : 1;
+ u32 reserved23 : 1;
+ u32 reserved24 : 1;
+ u32 reserved25 : 1;
+ u32 reserved26 : 1;
+ u32 enclave_mode : 1;
+ u32 smi_pending_mtf : 1;
+ u32 smi_from_vmx_root : 1;
+ u32 reserved30 : 1;
+ u32 failed_vmentry : 1;
+ };
+ u32 full;
+};
+
/*
* The nested_vmx structure is part of vcpu_vmx, and holds information we need
* for correct emulation of VMX (i.e., nested VMX) on this vcpu.
@@ -263,7 +286,7 @@ struct vcpu_vmx {
int vpid;
bool emulation_required;
- u32 exit_reason;
+ union vmx_exit_reason exit_reason;
/* Posted interrupt descriptor */
struct pi_desc pi_desc;
--
2.26.0
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