Commit fe0e80be authored by David Hildenbrand's avatar David Hildenbrand Committed by Paolo Bonzini
Browse files

KVM: VMX: drop vmm_exclusive module parameter 



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: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 33251870

arch/x86/kvm/vmx.c

+7 −31
Original line number Diff line number Diff line
@@ -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();

	}



	native_store_gdt(this_cpu_ptr(&host_gdt));
@@ -3489,16 +3471,14 @@ 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);

}



static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,

				      u32 msr, u32 *result)
@@ -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);

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