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KVM: VMX: drop vmm_exclusive module parameter

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vmm_exclusive=0 leads to KVM setting X86_CR4_VMXE always and calling
VMXON only when the vcpu is loaded. X86_CR4_VMXE is used as an
indication in cpu_emergency_vmxoff() (called on kdump) if VMXOFF has to be
called. This is obviously not the case if both are used independtly.
Calling VMXOFF without a previous VMXON will result in an exception.

In addition, X86_CR4_VMXE is used as a mean to test if VMX is already in
use by another VMM in hardware_enable(). So there can't really be
co-existance. If the other VMM is prepared for co-existance and does a
similar check, only one VMM can exist. If the other VMM is not prepared
and blindly sets/clears X86_CR4_VMXE, we will get inconsistencies with
X86_CR4_VMXE.

As we also had bug reports related to clearing of vmcs with vmm_exclusive=0
this seems to be pretty much untested. So let's better drop it.

While at it, directly move setting/clearing X86_CR4_VMXE into
kvm_cpu_vmxon/off.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Hildenbrand 2017-03-10 12:47:13 +01:00 committed by Paolo Bonzini
parent 3325187061
commit fe0e80befd
1 changed files with 7 additions and 31 deletions
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38
arch/x86/kvm/vmx.c
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@ -84,9 +84,6 @@ module_param_named(eptad, enable_ept_ad_bits, bool, S_IRUGO);
static bool __read_mostly emulate_invalid_guest_state = true;
module_param(emulate_invalid_guest_state, bool, S_IRUGO);
static bool __read_mostly vmm_exclusive = 1;
module_param(vmm_exclusive, bool, S_IRUGO);
static bool __read_mostly fasteoi = 1;
module_param(fasteoi, bool, S_IRUGO);
@ -910,8 +907,6 @@ static void nested_release_page_clean(struct page *page)
static unsigned long nested_ept_get_cr3(struct kvm_vcpu *vcpu);
static u64 construct_eptp(unsigned long root_hpa);
static void kvm_cpu_vmxon(u64 addr);
static void kvm_cpu_vmxoff(void);
static bool vmx_xsaves_supported(void);
static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
static void vmx_set_segment(struct kvm_vcpu *vcpu,
@ -2231,15 +2226,10 @@ static void decache_tsc_multiplier(struct vcpu_vmx *vmx)
static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
bool already_loaded = vmx->loaded_vmcs->cpu == cpu;
if (!vmm_exclusive)
kvm_cpu_vmxon(phys_addr);
else if (!already_loaded)
loaded_vmcs_clear(vmx->loaded_vmcs);
if (!already_loaded) {
loaded_vmcs_clear(vmx->loaded_vmcs);
local_irq_disable();
crash_disable_local_vmclear(cpu);
@ -2317,11 +2307,6 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
vmx_vcpu_pi_put(vcpu);
__vmx_load_host_state(to_vmx(vcpu));
if (!vmm_exclusive) {
__loaded_vmcs_clear(to_vmx(vcpu)->loaded_vmcs);
vcpu->cpu = -1;
kvm_cpu_vmxoff();
}
}
static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu);
@ -3416,6 +3401,7 @@ static __init int vmx_disabled_by_bios(void)
static void kvm_cpu_vmxon(u64 addr)
{
cr4_set_bits(X86_CR4_VMXE);
intel_pt_handle_vmx(1);
asm volatile (ASM_VMX_VMXON_RAX
@ -3458,12 +3444,8 @@ static int hardware_enable(void)
/* enable and lock */
wrmsrl(MSR_IA32_FEATURE_CONTROL, old | test_bits);
}
cr4_set_bits(X86_CR4_VMXE);
if (vmm_exclusive) {
kvm_cpu_vmxon(phys_addr);
ept_sync_global();
}
kvm_cpu_vmxon(phys_addr);
ept_sync_global();
native_store_gdt(this_cpu_ptr(&host_gdt));
@ -3489,15 +3471,13 @@ static void kvm_cpu_vmxoff(void)
asm volatile (__ex(ASM_VMX_VMXOFF) : : : "cc");
intel_pt_handle_vmx(0);
cr4_clear_bits(X86_CR4_VMXE);
}
static void hardware_disable(void)
{
if (vmm_exclusive) {
vmclear_local_loaded_vmcss();
kvm_cpu_vmxoff();
}
cr4_clear_bits(X86_CR4_VMXE);
vmclear_local_loaded_vmcss();
kvm_cpu_vmxoff();
}
static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,
@ -9170,11 +9150,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
vmx->loaded_vmcs->shadow_vmcs = NULL;
if (!vmx->loaded_vmcs->vmcs)
goto free_msrs;
if (!vmm_exclusive)
kvm_cpu_vmxon(__pa(per_cpu(vmxarea, raw_smp_processor_id())));
loaded_vmcs_init(vmx->loaded_vmcs);
if (!vmm_exclusive)
kvm_cpu_vmxoff();
cpu = get_cpu();
vmx_vcpu_load(&vmx->vcpu, cpu);