Commit 6e3ba4ab authored by Tao Xu's avatar Tao Xu Committed by Paolo Bonzini
Browse files

KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL 



UMWAIT and TPAUSE instructions use 32bit IA32_UMWAIT_CONTROL at MSR index
E1H to determines the maximum time in TSC-quanta that the processor can
reside in either C0.1 or C0.2.

This patch emulates MSR IA32_UMWAIT_CONTROL in guest and differentiate
IA32_UMWAIT_CONTROL between host and guest. The variable
mwait_control_cached in arch/x86/kernel/cpu/umwait.c caches the MSR value,
so this patch uses it to avoid frequently rdmsr of IA32_UMWAIT_CONTROL.

Co-developed-by: default avatarJingqi Liu <jingqi.liu@intel.com>
Signed-off-by: default avatarJingqi Liu <jingqi.liu@intel.com>
Signed-off-by: default avatarTao Xu <tao3.xu@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e69e72fa

arch/x86/kernel/cpu/umwait.c

+6 −0
Original line number Diff line number Diff line
@@ -17,6 +17,12 @@ 
 */

static u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLE);



u32 get_umwait_control_msr(void)

{

	return umwait_control_cached;

}

EXPORT_SYMBOL_GPL(get_umwait_control_msr);



/*

 * Cache the original IA32_UMWAIT_CONTROL MSR value which is configured by

 * hardware or BIOS before kernel boot.

arch/x86/kvm/vmx/vmx.c

+36 −0
Original line number Diff line number Diff line
@@ -1733,6 +1733,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
#endif

	case MSR_EFER:

		return kvm_get_msr_common(vcpu, msr_info);

	case MSR_IA32_UMWAIT_CONTROL:

		if (!msr_info->host_initiated && !vmx_has_waitpkg(vmx))

			return 1;



		msr_info->data = vmx->msr_ia32_umwait_control;

		break;

	case MSR_IA32_SPEC_CTRL:

		if (!msr_info->host_initiated &&

		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
@@ -1906,6 +1912,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
			return 1;

		vmcs_write64(GUEST_BNDCFGS, data);

		break;

	case MSR_IA32_UMWAIT_CONTROL:

		if (!msr_info->host_initiated && !vmx_has_waitpkg(vmx))

			return 1;



		/* The reserved bit 1 and non-32 bit [63:32] should be zero */

		if (data & (BIT_ULL(1) | GENMASK_ULL(63, 32)))

			return 1;



		vmx->msr_ia32_umwait_control = data;

		break;

	case MSR_IA32_SPEC_CTRL:

		if (!msr_info->host_initiated &&

		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
@@ -4211,6 +4227,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) 
	vmx->rmode.vm86_active = 0;

	vmx->spec_ctrl = 0;



	vmx->msr_ia32_umwait_control = 0;



	vcpu->arch.microcode_version = 0x100000000ULL;

	vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val();

	vmx->hv_deadline_tsc = -1;
@@ -6384,6 +6402,23 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx) 
					msrs[i].host, false);

}



static void atomic_switch_umwait_control_msr(struct vcpu_vmx *vmx)

{

	u32 host_umwait_control;



	if (!vmx_has_waitpkg(vmx))

		return;



	host_umwait_control = get_umwait_control_msr();



	if (vmx->msr_ia32_umwait_control != host_umwait_control)

		add_atomic_switch_msr(vmx, MSR_IA32_UMWAIT_CONTROL,

			vmx->msr_ia32_umwait_control,

			host_umwait_control, false);

	else

		clear_atomic_switch_msr(vmx, MSR_IA32_UMWAIT_CONTROL);

}



static void vmx_update_hv_timer(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6478,6 +6513,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) 
	pt_guest_enter(vmx);



	atomic_switch_perf_msrs(vmx);

	atomic_switch_umwait_control_msr(vmx);



	if (enable_preemption_timer)

		vmx_update_hv_timer(vcpu);

arch/x86/kvm/vmx/vmx.h

+9 −0
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ 
extern const u32 vmx_msr_index[];

extern u64 host_efer;



extern u32 get_umwait_control_msr(void);



#define MSR_TYPE_R	1

#define MSR_TYPE_W	2

#define MSR_TYPE_RW	3
@@ -211,6 +213,7 @@ struct vcpu_vmx { 
#endif



	u64		      spec_ctrl;

	u32		      msr_ia32_umwait_control;



	u32 secondary_exec_control;
@@ -497,6 +500,12 @@ static inline void decache_tsc_multiplier(struct vcpu_vmx *vmx) 
	vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio);

}



static inline bool vmx_has_waitpkg(struct vcpu_vmx *vmx)

{

	return vmx->secondary_exec_control &

		SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE;

}



void dump_vmcs(void);



#endif /* __KVM_X86_VMX_H */

arch/x86/kvm/x86.c

+2 −0
Original line number Diff line number Diff line
@@ -1145,6 +1145,8 @@ static u32 msrs_to_save[] = { 
	MSR_IA32_RTIT_ADDR1_A, MSR_IA32_RTIT_ADDR1_B,

	MSR_IA32_RTIT_ADDR2_A, MSR_IA32_RTIT_ADDR2_B,

	MSR_IA32_RTIT_ADDR3_A, MSR_IA32_RTIT_ADDR3_B,

	MSR_IA32_UMWAIT_CONTROL,



	MSR_ARCH_PERFMON_FIXED_CTR0, MSR_ARCH_PERFMON_FIXED_CTR1,

	MSR_ARCH_PERFMON_FIXED_CTR0 + 2, MSR_ARCH_PERFMON_FIXED_CTR0 + 3,

	MSR_CORE_PERF_FIXED_CTR_CTRL, MSR_CORE_PERF_GLOBAL_STATUS,

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