KVM: x86: Support for disabling quirks

Introducing KVM_CAP_DISABLE_QUIRKS for disabling x86 quirks that were previous
created in order to overcome QEMU issues. Those issue were mostly result of
invalid VM BIOS.  Currently there are two quirks that can be disabled:

1. KVM_QUIRK_LINT0_REENABLED - LINT0 was enabled after boot
2. KVM_QUIRK_CD_NW_CLEARED - CD and NW are cleared after boot

These two issues are already resolved in recent releases of QEMU, and would
therefore be disabled by QEMU.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Message-Id: <1428879221-29996-1-git-send-email-namit@cs.technion.ac.il>
[Report capability from KVM_CHECK_EXTENSION too. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 9fa2bf8c3f6f13282c92c33671b5ad9a3eaa1d0a..695544420ff265690917802e82a5bc2c57a4d578 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -959,7 +959,8 @@ documentation when it pops into existence).
 4.37 KVM_ENABLE_CAP
 
 Capability: KVM_CAP_ENABLE_CAP, KVM_CAP_ENABLE_CAP_VM
-Architectures: ppc, s390
+Architectures: x86 (only KVM_CAP_ENABLE_CAP_VM),
+              mips (only KVM_CAP_ENABLE_CAP), ppc, s390
 Type: vcpu ioctl, vm ioctl (with KVM_CAP_ENABLE_CAP_VM)
 Parameters: struct kvm_enable_cap (in)
 Returns: 0 on success; -1 on error

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index dea2e7e962e3e0648c9ecaaaffc5cb723b32f299..f80ad591aa612754570bdc9147feeb608af41e04 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -635,6 +635,8 @@ struct kvm_arch {
        #endif
 
        bool boot_vcpu_runs_old_kvmclock;
+
+       u64 disabled_quirks;
 };
 
 struct kvm_vm_stat {

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index d7dcef58aefa9c736efedcd6292bd0d539ac24a4..2fec75e4b1e1e219a34af450d35309642674dbd9 100644 (file)
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -345,4 +345,7 @@ struct kvm_xcrs {
 struct kvm_sync_regs {
 };
 
+#define KVM_QUIRK_LINT0_REENABLED      (1 << 0)
+#define KVM_QUIRK_CD_NW_CLEARED                (1 << 1)
+
 #endif /* _ASM_X86_KVM_H */

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 629af0f1c5c4d0953010adc88233132bcdff4cb7..4071eb161c8fa87df51110d4363a8d5326845b33 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1577,8 +1577,9 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu)
        for (i = 0; i < APIC_LVT_NUM; i++)
                apic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED);
        apic->lapic_timer.timer_mode = 0;
-       apic_set_reg(apic, APIC_LVT0,
-                    SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
+       if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_LINT0_REENABLED))
+               apic_set_reg(apic, APIC_LVT0,
+                            SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
 
        apic_set_reg(apic, APIC_DFR, 0xffffffffU);
        apic_set_spiv(apic, 0xff);

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ce741b8650f6ece694fb47e1750d153291a1803f..46299dac7c6def1d9035d5a9efacff0a9c570640 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1575,7 +1575,8 @@ static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
         * does not do it - this results in some delay at
         * reboot
         */
-       cr0 &= ~(X86_CR0_CD | X86_CR0_NW);
+       if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_CD_NW_CLEARED))
+               cr0 &= ~(X86_CR0_CD | X86_CR0_NW);
        svm->vmcb->save.cr0 = cr0;
        mark_dirty(svm->vmcb, VMCB_CR);
        update_cr0_intercept(svm);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7a959be0aebc1c4600e11ef8fadd96233e86fed8..0435b653f58389941ff88cb59fe3d199bb63bef6 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2800,6 +2800,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
        case KVM_CAP_HYPERV_TIME:
        case KVM_CAP_IOAPIC_POLARITY_IGNORED:
        case KVM_CAP_TSC_DEADLINE_TIMER:
+       case KVM_CAP_ENABLE_CAP_VM:
+       case KVM_CAP_DISABLE_QUIRKS:
 #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
        case KVM_CAP_ASSIGN_DEV_IRQ:
        case KVM_CAP_PCI_2_3:
@@ -3847,6 +3849,26 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event,
        return 0;
 }
 
+static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
+                                  struct kvm_enable_cap *cap)
+{
+       int r;
+
+       if (cap->flags)
+               return -EINVAL;
+
+       switch (cap->cap) {
+       case KVM_CAP_DISABLE_QUIRKS:
+               kvm->arch.disabled_quirks = cap->args[0];
+               r = 0;
+               break;
+       default:
+               r = -EINVAL;
+               break;
+       }
+       return r;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
                       unsigned int ioctl, unsigned long arg)
 {
@@ -4099,7 +4121,15 @@ long kvm_arch_vm_ioctl(struct file *filp,
                r = 0;
                break;
        }
+       case KVM_ENABLE_CAP: {
+               struct kvm_enable_cap cap;
 
+               r = -EFAULT;
+               if (copy_from_user(&cap, argp, sizeof(cap)))
+                       goto out;
+               r = kvm_vm_ioctl_enable_cap(kvm, &cap);
+               break;
+       }
        default:
                r = kvm_vm_ioctl_assigned_device(kvm, ioctl, arg);
        }

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 4b60056776d1484f4c6c43b6c4a1ef47a2592a61..75bd9f7fd8465d8008f7648a79bf4270bc4c8bfe 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -814,6 +814,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_S390_INJECT_IRQ 113
 #define KVM_CAP_S390_IRQ_STATE 114
 #define KVM_CAP_PPC_HWRNG 115
+#define KVM_CAP_DISABLE_QUIRKS 116
 
 #ifdef KVM_CAP_IRQ_ROUTING