[19/30] KVM: nSVM: extract svm_set_gif
diff mbox series

Message ID 20200529153934.11694-20-pbonzini@redhat.com
State New
Headers show
Series
  • KVM: nSVM: event fixes and migration support
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Commit Message

Paolo Bonzini May 29, 2020, 3:39 p.m. UTC
Extract the code that is needed to implement CLGI and STGI,
so that we can run it from VMRUN and vmexit (and in the future,
KVM_SET_NESTED_STATE).  Skip the request for KVM_REQ_EVENT unless needed,
subsuming the evaluate_pending_interrupts optimization that is found
in enter_svm_guest_mode.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/irq.c        |  1 +
 arch/x86/kvm/svm/nested.c | 22 ++---------------
 arch/x86/kvm/svm/svm.c    | 51 ++++++++++++++++++++++++++-------------
 arch/x86/kvm/svm/svm.h    |  1 +
 4 files changed, 38 insertions(+), 37 deletions(-)

Comments

Qian Cai June 5, 2020, 8:33 p.m. UTC | #1
On Fri, May 29, 2020 at 11:39:23AM -0400, Paolo Bonzini wrote:
> Extract the code that is needed to implement CLGI and STGI,
> so that we can run it from VMRUN and vmexit (and in the future,
> KVM_SET_NESTED_STATE).  Skip the request for KVM_REQ_EVENT unless needed,
> subsuming the evaluate_pending_interrupts optimization that is found
> in enter_svm_guest_mode.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/irq.c        |  1 +
>  arch/x86/kvm/svm/nested.c | 22 ++---------------
>  arch/x86/kvm/svm/svm.c    | 51 ++++++++++++++++++++++++++-------------
>  arch/x86/kvm/svm/svm.h    |  1 +
>  4 files changed, 38 insertions(+), 37 deletions(-)
[]
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1981,6 +1981,38 @@ static int vmrun_interception(struct vcpu_svm *svm)
>  	return nested_svm_vmrun(svm);
>  }
>  
> +void svm_set_gif(struct vcpu_svm *svm, bool value)
> +{
> +	if (value) {
> +		/*
> +		 * If VGIF is enabled, the STGI intercept is only added to
> +		 * detect the opening of the SMI/NMI window; remove it now.
> +		 * Likewise, clear the VINTR intercept, we will set it
> +		 * again while processing KVM_REQ_EVENT if needed.
> +		 */
> +		if (vgif_enabled(svm))
> +			clr_intercept(svm, INTERCEPT_STGI);
> +		if (is_intercept(svm, SVM_EXIT_VINTR))

A simple qemu-kvm will trigger the warning. (Looks like the patch had
already been pulled into the mainline quickly.)

# qemu-kvm -name ubuntu-18.04-server-cloudimg -cpu host -smp 2 -m 2G \
  -hda ubuntu-18.04-server-cloudimg.qcow2 \
  -cdrom ubuntu-18.04-server-cloudimg.iso -nic user,hostfwd=tcp::2222-:22 \
  -nographic -device vfio-pci,host=0000:04:0a.0

[ 1362.284812][ T2195] ================================================================================
[ 1362.294789][ T2195] UBSAN: shift-out-of-bounds in arch/x86/kvm/svm/svm.h:316:47
[ 1362.302209][ T2195] shift exponent 100 is too large for 64-bit type 'long long unsigned int'
[ 1362.310715][ T2195] CPU: 51 PID: 2195 Comm: qemu-kvm Not tainted 5.7.0-next-20200605 #6
[ 1362.319244][ T2195] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 03/09/2018
[ 1362.328530][ T2195] Call Trace:
[ 1362.331710][ T2195]  dump_stack+0xa7/0xea
[ 1362.335758][ T2195]  ubsan_epilogue+0x9/0x45
[ 1362.340070][ T2195]  __ubsan_handle_shift_out_of_bounds.cold.13+0x14/0x98
[ 1362.347386][ T2195]  ? __kasan_check_write+0x14/0x20
[ 1362.352405][ T2195]  ? set_msr_interception+0x1b8/0x300 [kvm_amd]
[ 1362.358558][ T2195]  svm_set_gif.cold.64+0x16/0xd1 [kvm_amd]
[ 1362.364276][ T2195]  svm_set_efer+0xbc/0xc0 [kvm_amd]
svm_set_efer at arch/x86/kvm/svm/svm.c:281
[ 1362.369866][ T2195]  init_vmcb+0x107c/0x1b80 [kvm_amd]
[ 1362.375056][ T2195]  svm_create_vcpu+0x237/0x360 [kvm_amd]
[ 1362.380677][ T2195]  kvm_arch_vcpu_create+0x490/0x5f0 [kvm]
[ 1362.386381][ T2195]  kvm_vm_ioctl+0x10c5/0x17f0 [kvm]
[ 1362.391561][ T2195]  ? kvm_unregister_device_ops+0xd0/0xd0 [kvm]
[ 1362.398118][ T2195]  ? validate_chain+0xab/0x1b30
[ 1362.402864][ T2195]  ? __kasan_check_read+0x11/0x20
[ 1362.407784][ T2195]  ? check_chain_key+0x1df/0x2e0
[ 1362.412615][ T2195]  ? __lock_acquire+0x74c/0xc10
[ 1362.417363][ T2195]  ? match_held_lock+0x20/0x2f0
[ 1362.422593][ T2195]  ? check_chain_key+0x1df/0x2e0
[ 1362.427425][ T2195]  ? find_held_lock+0xca/0xf0
[ 1362.431997][ T2195]  ? __fget_files+0x172/0x270
[ 1362.436565][ T2195]  ? lock_downgrade+0x3e0/0x3e0
[ 1362.441310][ T2195]  ? rcu_read_lock_held+0xac/0xc0
[ 1362.446744][ T2195]  ? rcu_read_lock_sched_held+0xe0/0xe0
[ 1362.452190][ T2195]  ? __fget_files+0x18c/0x270
[ 1362.456759][ T2195]  ? __fget_light+0xf2/0x110
[ 1362.461242][ T2195]  ksys_ioctl+0x26e/0xc60
[ 1362.465464][ T2195]  ? generic_block_fiemap+0x70/0x70
[ 1362.471024][ T2195]  ? find_held_lock+0xca/0xf0
[ 1362.475597][ T2195]  ? __task_pid_nr_ns+0x145/0x290
[ 1362.480517][ T2195]  ? check_flags.part.26+0x86/0x230
[ 1362.485613][ T2195]  ? __kasan_check_read+0x11/0x20
[ 1362.490535][ T2195]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1362.497009][ T2195]  ? do_syscall_64+0x23/0x340
[ 1362.501581][ T2195]  ? rcu_read_lock_sched_held+0xac/0xe0
[ 1362.507023][ T2195]  ? mark_held_locks+0x34/0xb0
[ 1362.511679][ T2195]  ? do_syscall_64+0x29/0x340
[ 1362.516254][ T2195]  __x64_sys_ioctl+0x43/0x4c
[ 1362.521177][ T2195]  do_syscall_64+0x64/0x340
[ 1362.525573][ T2195]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1362.531366][ T2195] RIP: 0033:0x7f8c609cb87b
[ 1362.535676][ T2195] Code: Bad RIP value.
[ 1362.539633][ T2195] RSP: 002b:00007f8c517fb6c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 1362.548399][ T2195] RAX: ffffffffffffffda RBX: 0000564c201f9110 RCX: 00007f8c609cb87b
[ 1362.556287][ T2195] RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 000000000000000a
[ 1362.564178][ T2195] RBP: 0000564c201f9110 R08: 0000564c1e47cd50 R09: 0000564c201f9110
[ 1362.572455][ T2195] R10: 0000564c1ebfd680 R11: 0000000000000246 R12: 0000564c201954d0
[ 1362.580344][ T2195] R13: 00007ffe3a592d6f R14: 00007ffe3a592e00 R15: 00007f8c517fb840
[ 1362.588287][ T2195] ================================================================================

> +			svm_clear_vintr(svm);
> +
> +		enable_gif(svm);
> +		if (svm->vcpu.arch.smi_pending ||
> +		    svm->vcpu.arch.nmi_pending ||
> +		    kvm_cpu_has_injectable_intr(&svm->vcpu))
> +			kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
> +	} else {
> +		disable_gif(svm);
> +
> +		/*
> +		 * After a CLGI no interrupts should come.  But if vGIF is
> +		 * in use, we still rely on the VINTR intercept (rather than
> +		 * STGI) to detect an open interrupt window.
> +		*/
> +		if (!vgif_enabled(svm))
> +			svm_clear_vintr(svm);
> +	}
> +}
> +
Paolo Bonzini June 8, 2020, 11:11 a.m. UTC | #2
On 05/06/20 22:33, Qian Cai wrote:
>> +	if (value) {
>> +		/*
>> +		 * If VGIF is enabled, the STGI intercept is only added to
>> +		 * detect the opening of the SMI/NMI window; remove it now.
>> +		 * Likewise, clear the VINTR intercept, we will set it
>> +		 * again while processing KVM_REQ_EVENT if needed.
>> +		 */
>> +		if (vgif_enabled(svm))
>> +			clr_intercept(svm, INTERCEPT_STGI);
>> +		if (is_intercept(svm, SVM_EXIT_VINTR))
> A simple qemu-kvm will trigger the warning. (Looks like the patch had
> already been pulled into the mainline quickly.)

You're right, that should have been INTERCEPT_VINTR.  I'll post a fix.

Thanks,

Paolo

Patch
diff mbox series

diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index 54f7ea68083b..99d118ffc67d 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -83,6 +83,7 @@  int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
 
 	return kvm_apic_has_interrupt(v) != -1; /* LAPIC */
 }
+EXPORT_SYMBOL_GPL(kvm_cpu_has_injectable_intr);
 
 /*
  * check if there is pending interrupt without
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 921466eba556..7e4a506828c9 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -333,10 +333,6 @@  static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
 void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 			  struct vmcb *nested_vmcb)
 {
-	bool evaluate_pending_interrupts =
-		is_intercept(svm, INTERCEPT_VINTR) ||
-		is_intercept(svm, INTERCEPT_IRET);
-
 	svm->nested.vmcb = vmcb_gpa;
 	if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
 		svm->vcpu.arch.hflags |= HF_HIF_MASK;
@@ -347,21 +343,7 @@  void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 	nested_prepare_vmcb_save(svm, nested_vmcb);
 	nested_prepare_vmcb_control(svm);
 
-	/*
-	 * If L1 had a pending IRQ/NMI before executing VMRUN,
-	 * which wasn't delivered because it was disallowed (e.g.
-	 * interrupts disabled), L0 needs to evaluate if this pending
-	 * event should cause an exit from L2 to L1 or be delivered
-	 * directly to L2.
-	 *
-	 * Usually this would be handled by the processor noticing an
-	 * IRQ/NMI window request.  However, VMRUN can unblock interrupts
-	 * by implicitly setting GIF, so force L0 to perform pending event
-	 * evaluation by requesting a KVM_REQ_EVENT.
-	 */
-	enable_gif(svm);
-	if (unlikely(evaluate_pending_interrupts))
-		kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+	svm_set_gif(svm, true);
 }
 
 int nested_svm_vmrun(struct vcpu_svm *svm)
@@ -505,7 +487,7 @@  int nested_svm_vmexit(struct vcpu_svm *svm)
 	svm->vcpu.arch.mp_state = KVM_MP_STATE_RUNNABLE;
 
 	/* Give the current vmcb to the guest */
-	disable_gif(svm);
+	svm_set_gif(svm, false);
 
 	nested_vmcb->save.es     = vmcb->save.es;
 	nested_vmcb->save.cs     = vmcb->save.cs;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7383f821eb3b..e48e4173bc60 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1981,6 +1981,38 @@  static int vmrun_interception(struct vcpu_svm *svm)
 	return nested_svm_vmrun(svm);
 }
 
+void svm_set_gif(struct vcpu_svm *svm, bool value)
+{
+	if (value) {
+		/*
+		 * If VGIF is enabled, the STGI intercept is only added to
+		 * detect the opening of the SMI/NMI window; remove it now.
+		 * Likewise, clear the VINTR intercept, we will set it
+		 * again while processing KVM_REQ_EVENT if needed.
+		 */
+		if (vgif_enabled(svm))
+			clr_intercept(svm, INTERCEPT_STGI);
+		if (is_intercept(svm, SVM_EXIT_VINTR))
+			svm_clear_vintr(svm);
+
+		enable_gif(svm);
+		if (svm->vcpu.arch.smi_pending ||
+		    svm->vcpu.arch.nmi_pending ||
+		    kvm_cpu_has_injectable_intr(&svm->vcpu))
+			kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+	} else {
+		disable_gif(svm);
+
+		/*
+		 * After a CLGI no interrupts should come.  But if vGIF is
+		 * in use, we still rely on the VINTR intercept (rather than
+		 * STGI) to detect an open interrupt window.
+		*/
+		if (!vgif_enabled(svm))
+			svm_clear_vintr(svm);
+	}
+}
+
 static int stgi_interception(struct vcpu_svm *svm)
 {
 	int ret;
@@ -1988,18 +2020,8 @@  static int stgi_interception(struct vcpu_svm *svm)
 	if (nested_svm_check_permissions(svm))
 		return 1;
 
-	/*
-	 * If VGIF is enabled, the STGI intercept is only added to
-	 * detect the opening of the SMI/NMI window; remove it now.
-	 */
-	if (vgif_enabled(svm))
-		clr_intercept(svm, INTERCEPT_STGI);
-
 	ret = kvm_skip_emulated_instruction(&svm->vcpu);
-	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
-
-	enable_gif(svm);
-
+	svm_set_gif(svm, true);
 	return ret;
 }
 
@@ -2011,12 +2033,7 @@  static int clgi_interception(struct vcpu_svm *svm)
 		return 1;
 
 	ret = kvm_skip_emulated_instruction(&svm->vcpu);
-
-	disable_gif(svm);
-
-	/* After a CLGI no interrupts should come */
-	svm_clear_vintr(svm);
-
+	svm_set_gif(svm, false);
 	return ret;
 }
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 7e79f0af1204..10b7b55720a0 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -357,6 +357,7 @@  void disable_nmi_singlestep(struct vcpu_svm *svm);
 bool svm_smi_blocked(struct kvm_vcpu *vcpu);
 bool svm_nmi_blocked(struct kvm_vcpu *vcpu);
 bool svm_interrupt_blocked(struct kvm_vcpu *vcpu);
+void svm_set_gif(struct vcpu_svm *svm, bool value);
 
 /* nested.c */