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KVM: x86: do not spam dmesg with VMCS/VMCB dumps 

Userspace can easily set up invalid processor state in such a way that
dmesg will be filled with VMCS or VMCB dumps.  Disable this by default
using a module parameter.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2019-05-20 15:34:35 +02:00
parent 654f1f13ea
commit 6f2f84532c
2 changed files with 27 additions and 8 deletions
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9
arch/x86/kvm/svm.c
View File

@ -379,6 +379,9 @@ module_param(vgif, int, 0444);
static int sev = IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT);
module_param(sev, int, 0444);
static bool __read_mostly dump_invalid_vmcb = 0;
module_param(dump_invalid_vmcb, bool, 0644);
static u8 rsm_ins_bytes[] = "\x0f\xaa";
static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
@ -4828,6 +4831,11 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
struct vmcb_control_area *control = &svm->vmcb->control;
struct vmcb_save_area *save = &svm->vmcb->save;
if (!dump_invalid_vmcb) {
pr_warn_ratelimited("set kvm_amd.dump_invalid_vmcb=1 to dump internal KVM state.\n");
return;
}
pr_err("VMCB Control Area:\n");
pr_err("%-20s%04x\n", "cr_read:", control->intercept_cr & 0xffff);
pr_err("%-20s%04x\n", "cr_write:", control->intercept_cr >> 16);
@ -4986,7 +4994,6 @@ static int handle_exit(struct kvm_vcpu *vcpu)
kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
kvm_run->fail_entry.hardware_entry_failure_reason
= svm->vmcb->control.exit_code;
pr_err("KVM: FAILED VMRUN WITH VMCB:\n");
dump_vmcb(vcpu);
return 0;
}

26
arch/x86/kvm/vmx/vmx.c
View File

@ -114,6 +114,9 @@ static u64 __read_mostly host_xss;
bool __read_mostly enable_pml = 1;
module_param_named(pml, enable_pml, bool, S_IRUGO);
static bool __read_mostly dump_invalid_vmcs = 0;
module_param(dump_invalid_vmcs, bool, 0644);
#define MSR_BITMAP_MODE_X2APIC 1
#define MSR_BITMAP_MODE_X2APIC_APICV 2
@ -5607,15 +5610,24 @@ static void vmx_dump_dtsel(char *name, uint32_t limit)
void dump_vmcs(void)
{
u32 vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS);
u32 vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS);
u32 cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
u32 pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
u32 secondary_exec_control = 0;
unsigned long cr4 = vmcs_readl(GUEST_CR4);
u64 efer = vmcs_read64(GUEST_IA32_EFER);
u32 vmentry_ctl, vmexit_ctl;
u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
unsigned long cr4;
u64 efer;
int i, n;
if (!dump_invalid_vmcs) {
pr_warn_ratelimited("set kvm_intel.dump_invalid_vmcs=1 to dump internal KVM state.\n");
return;
}
vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS);
vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS);
cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
cr4 = vmcs_readl(GUEST_CR4);
efer = vmcs_read64(GUEST_IA32_EFER);
secondary_exec_control = 0;
if (cpu_has_secondary_exec_ctrls())
secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);