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Commit d7ee039e authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: vmx: move struct host_state usage to struct loaded_vmcs 



Make host_state a property of a loaded_vmcs so that it can be
used as a cache of the VMCS fields, e.g. to lazily VMWRITE the
corresponding VMCS field.  Treating host_state as a cache does
not work if it's not VMCS specific as the cache would become
incoherent when switching between vmcs01 and vmcs02.

Move vmcs_host_cr3 and vmcs_host_cr4 into host_state.

Explicitly zero out host_state when allocating a new VMCS for a
loaded_vmcs.  Unlike the pre-existing vmcs_host_cr{3,4} usage,
the segment information is not guaranteed to be (re)initialized
when running a new nested VMCS, e.g. HOST_FS_BASE is not written
in vmx_set_constant_host_state().

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e920de85

arch/x86/kvm/vmx.c

+44 −28
Original line number Diff line number Diff line
@@ -218,6 +218,21 @@ struct vmcs { 
	char data[0];

};



/*

 * vmcs_host_state tracks registers that are loaded from the VMCS on VMEXIT

 * and whose values change infrequently, but are not constant.  I.e. this is

 * used as a write-through cache of the corresponding VMCS fields.

 */

struct vmcs_host_state {

	unsigned long cr3;	/* May not match real cr3 */

	unsigned long cr4;	/* May not match real cr4 */



	u16           fs_sel, gs_sel, ldt_sel;

#ifdef CONFIG_X86_64

	u16           ds_sel, es_sel;

#endif

};



/*

 * Track a VMCS that may be loaded on a certain CPU. If it is (cpu!=-1), also

 * remember whether it was VMLAUNCHed, and maintain a linked list of all VMCSs
@@ -229,14 +244,13 @@ struct loaded_vmcs { 
	int cpu;

	bool launched;

	bool nmi_known_unmasked;

	unsigned long vmcs_host_cr3;	/* May not match real cr3 */

	unsigned long vmcs_host_cr4;	/* May not match real cr4 */

	/* Support for vnmi-less CPUs */

	int soft_vnmi_blocked;

	ktime_t entry_time;

	s64 vnmi_blocked_time;

	unsigned long *msr_bitmap;

	struct list_head loaded_vmcss_on_cpu_link;

	struct vmcs_host_state host_state;

};



struct shared_msr_entry {
@@ -819,12 +833,6 @@ struct vcpu_vmx { 
		struct vmx_msr_entry host[NR_AUTOLOAD_MSRS];

	} msr_autoload;



	struct {

		u16           fs_sel, gs_sel, ldt_sel;

#ifdef CONFIG_X86_64

		u16           ds_sel, es_sel;

#endif

	} host_state;

	struct {

		int vm86_active;

		ulong save_rflags;
@@ -2662,6 +2670,7 @@ static unsigned long segment_base(u16 selector) 
static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	struct vmcs_host_state *host_state;

#ifdef CONFIG_X86_64

	int cpu = raw_smp_processor_id();

#endif
@@ -2673,16 +2682,17 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) 
		return;



	vmx->loaded_cpu_state = vmx->loaded_vmcs;

	host_state = &vmx->loaded_cpu_state->host_state;



	/*

	 * Set host fs and gs selectors.  Unfortunately, 22.2.3 does not

	 * allow segment selectors with cpl > 0 or ti == 1.

	 */

	vmx->host_state.ldt_sel = kvm_read_ldt();

	host_state->ldt_sel = kvm_read_ldt();



#ifdef CONFIG_X86_64

	savesegment(ds, vmx->host_state.ds_sel);

	savesegment(es, vmx->host_state.es_sel);

	savesegment(ds, host_state->ds_sel);

	savesegment(es, host_state->es_sel);



	gs_base = cpu_kernelmode_gs_base(cpu);

	if (likely(is_64bit_mm(current->mm))) {
@@ -2707,12 +2717,12 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) 
	gs_base = segment_base(gs_sel);

#endif



	vmx->host_state.fs_sel = fs_sel;

	host_state->fs_sel = fs_sel;

	if (!(fs_sel & 7))

		vmcs_write16(HOST_FS_SELECTOR, fs_sel);

	else

		vmcs_write16(HOST_FS_SELECTOR, 0);

	vmx->host_state.gs_sel = gs_sel;

	host_state->gs_sel = gs_sel;

	if (!(gs_sel & 7))

		vmcs_write16(HOST_GS_SELECTOR, gs_sel);

	else
@@ -2729,10 +2739,13 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) 


static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)

{

	struct vmcs_host_state *host_state;



	if (!vmx->loaded_cpu_state)

		return;



	WARN_ON_ONCE(vmx->loaded_cpu_state != vmx->loaded_vmcs);

	host_state = &vmx->loaded_cpu_state->host_state;



	++vmx->vcpu.stat.host_state_reload;

	vmx->loaded_cpu_state = NULL;
@@ -2741,20 +2754,20 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx) 
	if (is_long_mode(&vmx->vcpu))

		rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);

#endif

	if (vmx->host_state.ldt_sel || (vmx->host_state.gs_sel & 7)) {

		kvm_load_ldt(vmx->host_state.ldt_sel);

	if (host_state->ldt_sel || (host_state->gs_sel & 7)) {

		kvm_load_ldt(host_state->ldt_sel);

#ifdef CONFIG_X86_64

		load_gs_index(vmx->host_state.gs_sel);

		load_gs_index(host_state->gs_sel);

#else

		loadsegment(gs, vmx->host_state.gs_sel);

		loadsegment(gs, host_state->gs_sel);

#endif

	}

	if (vmx->host_state.fs_sel & 7)

		loadsegment(fs, vmx->host_state.fs_sel);

	if (host_state->fs_sel & 7)

		loadsegment(fs, host_state->fs_sel);

#ifdef CONFIG_X86_64

	if (unlikely(vmx->host_state.ds_sel | vmx->host_state.es_sel)) {

		loadsegment(ds, vmx->host_state.ds_sel);

		loadsegment(es, vmx->host_state.es_sel);

	if (unlikely(host_state->ds_sel | host_state->es_sel)) {

		loadsegment(ds, host_state->ds_sel);

		loadsegment(es, host_state->es_sel);

	}

#endif

	invalidate_tss_limit();
@@ -4574,6 +4587,9 @@ static int alloc_loaded_vmcs(struct loaded_vmcs *loaded_vmcs) 
			evmcs->hv_enlightenments_control.msr_bitmap = 1;

		}

	}



	memset(&loaded_vmcs->host_state, 0, sizeof(struct vmcs_host_state));



	return 0;



out_vmcs:
@@ -6080,12 +6096,12 @@ static void vmx_set_constant_host_state(struct vcpu_vmx *vmx) 
	 */

	cr3 = __read_cr3();

	vmcs_writel(HOST_CR3, cr3);		/* 22.2.3  FIXME: shadow tables */

	vmx->loaded_vmcs->vmcs_host_cr3 = cr3;

	vmx->loaded_vmcs->host_state.cr3 = cr3;



	/* Save the most likely value for this task's CR4 in the VMCS. */

	cr4 = cr4_read_shadow();

	vmcs_writel(HOST_CR4, cr4);			/* 22.2.3, 22.2.5 */

	vmx->loaded_vmcs->vmcs_host_cr4 = cr4;

	vmx->loaded_vmcs->host_state.cr4 = cr4;



	vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS);  /* 22.2.4 */

#ifdef CONFIG_X86_64
@@ -10356,15 +10372,15 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) 
		vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);



	cr3 = __get_current_cr3_fast();

	if (unlikely(cr3 != vmx->loaded_vmcs->vmcs_host_cr3)) {

	if (unlikely(cr3 != vmx->loaded_vmcs->host_state.cr3)) {

		vmcs_writel(HOST_CR3, cr3);

		vmx->loaded_vmcs->vmcs_host_cr3 = cr3;

		vmx->loaded_vmcs->host_state.cr3 = cr3;

	}



	cr4 = cr4_read_shadow();

	if (unlikely(cr4 != vmx->loaded_vmcs->vmcs_host_cr4)) {

	if (unlikely(cr4 != vmx->loaded_vmcs->host_state.cr4)) {

		vmcs_writel(HOST_CR4, cr4);

		vmx->loaded_vmcs->vmcs_host_cr4 = cr4;

		vmx->loaded_vmcs->host_state.cr4 = cr4;

	}



	/* When single-stepping over STI and MOV SS, we must clear the