linux-kernel - Re: [PATCH 7/7] KVM: VMX: Introduce test mode related to EPT violation VE

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Date: Wed, 15 May 2024 16:38:47 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
	Isaku Yamahata <isaku.yamahata@...el.com>
Subject: Re: [PATCH 7/7] KVM: VMX: Introduce test mode related to EPT
 violation VE

On Tue, May 07, 2024, Paolo Bonzini wrote:
> @@ -5200,6 +5215,9 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
>  	if (is_invalid_opcode(intr_info))
>  		return handle_ud(vcpu);
>  
> +	if (KVM_BUG_ON(is_ve_fault(intr_info), vcpu->kvm))
> +		return -EIO;

I've hit this three times now when running KVM-Unit-Tests (I'm pretty sure it's
the EPT test, unsurprisingly).  And unless I screwed up my testing, I verified it
still fires with Isaku's fix[*], though I'm suddenly having problems repro'ing.

I'll update tomorrow as to whether I botched my testing of Isaku's fix, or if
there's another bug lurking.

https://lore.kernel.org/all/20240515173209.GD168153@ls.amr.corp.intel.com

  ------------[ cut here ]------------
  WARNING: CPU: 6 PID: 68167 at arch/x86/kvm/vmx/vmx.c:5217 handle_exception_nmi+0xd4/0x5b0 [kvm_intel]
  Modules linked in: kvm_intel kvm vfat fat dummy bridge stp llc spidev cdc_ncm cdc_eem cdc_ether usbnet mii xhci_pci xhci_hcd ehci_pci ehci_hcd gq(O) sha3_generic
  CPU: 6 PID: 68167 Comm: qemu Tainted: G S         O       6.9.0-smp--a3fee713d124-sigh #308
  Hardware name: Google Interlaken/interlaken, BIOS 0.20231025.0-0 10/25/2023
  RIP: 0010:handle_exception_nmi+0xd4/0x5b0 [kvm_intel]
  Code: 03 00 80 75 4e 48 89 df be 07 00 00 00 e8 24 79 e7 ff b8 01 00 00 00 eb bd 48 8b 0b b8 fb ff ff ff 80 b9 11 9f 00 00 00 75 ac <0f> 0b 48 8b 3b 66 c7 87 11 9f 00 00 01 01 be 01 03 00 00 e8 f4 66
  RSP: 0018:ff201f9afeebfb38 EFLAGS: 00010246
  RAX: 00000000fffffffb RBX: ff201f5bea710000 RCX: ff43efc142e18000
  RDX: 4813020000000002 RSI: 0000000000000000 RDI: ff201f5bea710000
  RBP: ff201f9afeebfb70 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000000 R11: ffffffffc0a3cd40 R12: 0000000080000300
  R13: 0000000000000000 R14: 0000000080000314 R15: 0000000080000314
  FS:  00007f65328006c0(0000) GS:ff201f993df00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000000 CR3: 00000040b5712002 CR4: 0000000000773ef0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
   <TASK>
   vmx_handle_exit+0x565/0x7e0 [kvm_intel]
   vcpu_run+0x188b/0x22b0 [kvm]
   kvm_arch_vcpu_ioctl_run+0x358/0x680 [kvm]
   kvm_vcpu_ioctl+0x4ca/0x5b0 [kvm]
   __se_sys_ioctl+0x7b/0xd0
   __x64_sys_ioctl+0x21/0x30
   x64_sys_call+0x15ac/0x2e40
   do_syscall_64+0x85/0x160
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
  RIP: 0033:0x7f653422bfbb
   </TASK>
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff85101206>] copy_process+0x366/0x13b0
  softirqs last  enabled at (0): [<ffffffff85101206>] copy_process+0x366/0x13b0
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace 0000000000000000 ]---