pending-5.1/kvm-x86-do-not-spam-dmesg-with-vmcs-vmcb-dumps.patch

   1 From c688492f62bfa80ecc3d2b966489ef2188bf166a Mon Sep 17 00:00:00 2001
   2 From: Paolo Bonzini <pbonzini@redhat.com>
   3 Date: Mon, 20 May 2019 15:34:35 +0200
   4 Subject: KVM: x86: do not spam dmesg with VMCS/VMCB dumps
   5
   6 [ Upstream commit 6f2f84532c153d32a5e53b6083b06a3e24368d30 ]
   7
   8 Userspace can easily set up invalid processor state in such a way that
   9 dmesg will be filled with VMCS or VMCB dumps.  Disable this by default
  10 using a module parameter.
  11
  12 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  13 Signed-off-by: Sasha Levin <sashal@kernel.org>
  14 ---
  15  arch/x86/kvm/svm.c     |  9 ++++++++-
  16  arch/x86/kvm/vmx/vmx.c | 26 +++++++++++++++++++-------
  17  2 files changed, 27 insertions(+), 8 deletions(-)
  18
  19 diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
  20 index ae6e51828a54..aa3b77acfbf9 100644
  21 --- a/arch/x86/kvm/svm.c
  22 +++ b/arch/x86/kvm/svm.c
  23 @@ -379,6 +379,9 @@ module_param(vgif, int, 0444);
  24  static int sev = IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT);
  25  module_param(sev, int, 0444);
  26
  27 +static bool __read_mostly dump_invalid_vmcb = 0;
  28 +module_param(dump_invalid_vmcb, bool, 0644);
  29 +
  30  static u8 rsm_ins_bytes[] = "\x0f\xaa";
  31
  32  static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
  33 @@ -4834,6 +4837,11 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
  34         struct vmcb_control_area *control = &svm->vmcb->control;
  35         struct vmcb_save_area *save = &svm->vmcb->save;
  36
  37 +       if (!dump_invalid_vmcb) {
  38 +               pr_warn_ratelimited("set kvm_amd.dump_invalid_vmcb=1 to dump internal KVM state.\n");
  39 +               return;
  40 +       }
  41 +
  42         pr_err("VMCB Control Area:\n");
  43         pr_err("%-20s%04x\n", "cr_read:", control->intercept_cr & 0xffff);
  44         pr_err("%-20s%04x\n", "cr_write:", control->intercept_cr >> 16);
  45 @@ -4992,7 +5000,6 @@ static int handle_exit(struct kvm_vcpu *vcpu)
  46                 kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
  47                 kvm_run->fail_entry.hardware_entry_failure_reason
  48                         = svm->vmcb->control.exit_code;
  49 -               pr_err("KVM: FAILED VMRUN WITH VMCB:\n");
  50                 dump_vmcb(vcpu);
  51                 return 0;
  52         }
  53 diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
  54 index 2b4a3d32c511..cfb8f1ec9a0a 100644
  55 --- a/arch/x86/kvm/vmx/vmx.c
  56 +++ b/arch/x86/kvm/vmx/vmx.c
  57 @@ -114,6 +114,9 @@ static u64 __read_mostly host_xss;
  58  bool __read_mostly enable_pml = 1;
  59  module_param_named(pml, enable_pml, bool, S_IRUGO);
  60
  61 +static bool __read_mostly dump_invalid_vmcs = 0;
  62 +module_param(dump_invalid_vmcs, bool, 0644);
  63 +
  64  #define MSR_BITMAP_MODE_X2APIC         1
  65  #define MSR_BITMAP_MODE_X2APIC_APICV   2
  66
  67 @@ -5605,15 +5608,24 @@ static void vmx_dump_dtsel(char *name, uint32_t limit)
  68
  69  void dump_vmcs(void)
  70  {
  71 -       u32 vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS);
  72 -       u32 vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS);
  73 -       u32 cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
  74 -       u32 pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
  75 -       u32 secondary_exec_control = 0;
  76 -       unsigned long cr4 = vmcs_readl(GUEST_CR4);
  77 -       u64 efer = vmcs_read64(GUEST_IA32_EFER);
  78 +       u32 vmentry_ctl, vmexit_ctl;
  79 +       u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
  80 +       unsigned long cr4;
  81 +       u64 efer;
  82         int i, n;
  83
  84 +       if (!dump_invalid_vmcs) {
  85 +               pr_warn_ratelimited("set kvm_intel.dump_invalid_vmcs=1 to dump internal KVM state.\n");
  86 +               return;
  87 +       }
  88 +
  89 +       vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS);
  90 +       vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS);
  91 +       cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
  92 +       pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
  93 +       cr4 = vmcs_readl(GUEST_CR4);
  94 +       efer = vmcs_read64(GUEST_IA32_EFER);
  95 +       secondary_exec_control = 0;
  96         if (cpu_has_secondary_exec_ctrls())
  97                 secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
  98
  99 --
 100 2.20.1
 101