Commit f5f48ee1 authored by Sheng Yang's avatar Sheng Yang Committed by Avi Kivity
Browse files

KVM: VMX: Execute WBINVD to keep data consistency with assigned devices 



Some guest device driver may leverage the "Non-Snoop" I/O, and explicitly
WBINVD or CLFLUSH to a RAM space. Since migration may occur before WBINVD or
CLFLUSH, we need to maintain data consistency either by:
1: flushing cache (wbinvd) when the guest is scheduled out if there is no
wbinvd exit, or
2: execute wbinvd on all dirty physical CPUs when guest wbinvd exits.

Signed-off-by: default avatarYaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: default avatarSheng Yang <sheng@linux.intel.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent cf3e3d3e

arch/x86/include/asm/kvm_host.h

+6 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/mm.h>

#include <linux/mmu_notifier.h>

#include <linux/tracepoint.h>

#include <linux/cpumask.h>



#include <linux/kvm.h>

#include <linux/kvm_para.h>
@@ -358,6 +359,8 @@ struct kvm_vcpu_arch { 


	/* fields used by HYPER-V emulation */

	u64 hv_vapic;



	cpumask_var_t wbinvd_dirty_mask;

};



struct kvm_arch {
@@ -514,6 +517,8 @@ struct kvm_x86_ops { 


	void (*set_supported_cpuid)(u32 func, struct kvm_cpuid_entry2 *entry);



	bool (*has_wbinvd_exit)(void);



	const struct trace_print_flags *exit_reasons_str;

};
@@ -571,6 +576,7 @@ void kvm_emulate_cpuid(struct kvm_vcpu *vcpu); 
int kvm_emulate_halt(struct kvm_vcpu *vcpu);

int emulate_invlpg(struct kvm_vcpu *vcpu, gva_t address);

int emulate_clts(struct kvm_vcpu *vcpu);

int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu);



void kvm_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);

int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector, int seg);

arch/x86/kvm/emulate.c

+4 −1
Original line number Diff line number Diff line
@@ -3138,8 +3138,11 @@ twobyte_insn: 
		emulate_clts(ctxt->vcpu);

		c->dst.type = OP_NONE;

		break;

	case 0x08:		/* invd */

	case 0x09:		/* wbinvd */

		kvm_emulate_wbinvd(ctxt->vcpu);

		c->dst.type = OP_NONE;

		break;

	case 0x08:		/* invd */

	case 0x0d:		/* GrpP (prefetch) */

	case 0x18:		/* Grp16 (prefetch/nop) */

		c->dst.type = OP_NONE;

arch/x86/kvm/svm.c

+7 −0
Original line number Diff line number Diff line
@@ -3424,6 +3424,11 @@ static bool svm_rdtscp_supported(void) 
	return false;

}



static bool svm_has_wbinvd_exit(void)

{

	return true;

}



static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);
@@ -3508,6 +3513,8 @@ static struct kvm_x86_ops svm_x86_ops = { 
	.rdtscp_supported = svm_rdtscp_supported,



	.set_supported_cpuid = svm_set_supported_cpuid,



	.has_wbinvd_exit = svm_has_wbinvd_exit,

};



static int __init svm_init(void)

arch/x86/kvm/vmx.c

+9 −1
Original line number Diff line number Diff line
@@ -412,6 +412,12 @@ static inline bool cpu_has_virtual_nmis(void) 
	return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS;

}



static inline bool cpu_has_vmx_wbinvd_exit(void)

{

	return vmcs_config.cpu_based_2nd_exec_ctrl &

		SECONDARY_EXEC_WBINVD_EXITING;

}



static inline bool report_flexpriority(void)

{

	return flexpriority_enabled;
@@ -3397,7 +3403,7 @@ static int handle_invlpg(struct kvm_vcpu *vcpu) 
static int handle_wbinvd(struct kvm_vcpu *vcpu)

{

	skip_emulated_instruction(vcpu);

	/* TODO: Add support for VT-d/pass-through device */

	kvm_emulate_wbinvd(vcpu);

	return 1;

}
@@ -4347,6 +4353,8 @@ static struct kvm_x86_ops vmx_x86_ops = { 
	.rdtscp_supported = vmx_rdtscp_supported,



	.set_supported_cpuid = vmx_set_supported_cpuid,



	.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,

};



static int __init vmx_init(void)

arch/x86/kvm/x86.c

+41 −0
Original line number Diff line number Diff line
@@ -1783,8 +1783,28 @@ out: 
	return r;

}



static void wbinvd_ipi(void *garbage)

{

	wbinvd();

}



static bool need_emulate_wbinvd(struct kvm_vcpu *vcpu)

{

	return vcpu->kvm->arch.iommu_domain &&

		!(vcpu->kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY);

}



void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

{

	/* Address WBINVD may be executed by guest */

	if (need_emulate_wbinvd(vcpu)) {

		if (kvm_x86_ops->has_wbinvd_exit())

			cpumask_set_cpu(cpu, vcpu->arch.wbinvd_dirty_mask);

		else if (vcpu->cpu != -1 && vcpu->cpu != cpu)

			smp_call_function_single(vcpu->cpu,

					wbinvd_ipi, NULL, 1);

	}



	kvm_x86_ops->vcpu_load(vcpu, cpu);

	if (unlikely(per_cpu(cpu_tsc_khz, cpu) == 0)) {

		unsigned long khz = cpufreq_quick_get(cpu);
@@ -3660,6 +3680,21 @@ int emulate_invlpg(struct kvm_vcpu *vcpu, gva_t address) 
	return X86EMUL_CONTINUE;

}



int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu)

{

	if (!need_emulate_wbinvd(vcpu))

		return X86EMUL_CONTINUE;



	if (kvm_x86_ops->has_wbinvd_exit()) {

		smp_call_function_many(vcpu->arch.wbinvd_dirty_mask,

				wbinvd_ipi, NULL, 1);

		cpumask_clear(vcpu->arch.wbinvd_dirty_mask);

	}

	wbinvd();

	return X86EMUL_CONTINUE;

}

EXPORT_SYMBOL_GPL(kvm_emulate_wbinvd);



int emulate_clts(struct kvm_vcpu *vcpu)

{

	kvm_x86_ops->set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~X86_CR0_TS));
@@ -5263,6 +5298,7 @@ void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu) 
		vcpu->arch.time_page = NULL;

	}



	free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);

	fx_free(vcpu);

	kvm_x86_ops->vcpu_free(vcpu);

}
@@ -5392,7 +5428,12 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) 
	}

	vcpu->arch.mcg_cap = KVM_MAX_MCE_BANKS;



	if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask, GFP_KERNEL))

		goto fail_free_mce_banks;



	return 0;

fail_free_mce_banks:

	kfree(vcpu->arch.mce_banks);

fail_free_lapic:

	kvm_free_lapic(vcpu);

fail_mmu_destroy:

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