Commit 60574973 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86: Rework KVM_REQ_MSR_FILTER_CHANGED into a generic RECALC_INTERCEPTS 



Rework the MSR_FILTER_CHANGED request into a more generic RECALC_INTERCEPTS
request, and expand the responsibilities of vendor code to recalculate all
intercepts that vary based on userspace input, e.g. instruction intercepts
that are tied to guest CPUID.

Providing a generic recalc request will allow the upcoming mediated PMU
support to trigger a recalc when PMU features, e.g. PERF_CAPABILITIES, are
set by userspace, without having to make multiple calls to/from PMU code.
As a bonus, using a request will effectively coalesce recalcs, e.g. will
reduce the number of recalcs for normal usage from 3+ to 1 (vCPU create,
set CPUID, set PERF_CAPABILITIES (Intel only), set filter).

The downside is that MSR filter changes that are done in isolation will do
a small amount of unnecessary work, but that's already a relatively slow
path, and the cost of recalculating instruction intercepts is negligible.

Tested-by: default avatarXudong Hao <xudong.hao@intel.com>
Link: https://lore.kernel.org/r/20250806195706.1650976-25-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent cdfed937

arch/x86/include/asm/kvm-x86-ops.h

+1 −1
Original line number Diff line number Diff line
@@ -138,7 +138,7 @@ KVM_X86_OP(check_emulate_instruction) 
KVM_X86_OP(apic_init_signal_blocked)

KVM_X86_OP_OPTIONAL(enable_l2_tlb_flush)

KVM_X86_OP_OPTIONAL(migrate_timers)

KVM_X86_OP(recalc_msr_intercepts)

KVM_X86_OP(recalc_intercepts)

KVM_X86_OP(complete_emulated_msr)

KVM_X86_OP(vcpu_deliver_sipi_vector)

KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);

arch/x86/include/asm/kvm_host.h

+2 −2
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ 
#define KVM_REQ_TLB_FLUSH_GUEST \

	KVM_ARCH_REQ_FLAGS(27, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)

#define KVM_REQ_APF_READY		KVM_ARCH_REQ(28)

#define KVM_REQ_MSR_FILTER_CHANGED	KVM_ARCH_REQ(29)

#define KVM_REQ_RECALC_INTERCEPTS	KVM_ARCH_REQ(29)

#define KVM_REQ_UPDATE_CPU_DIRTY_LOGGING \

	KVM_ARCH_REQ_FLAGS(30, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)

#define KVM_REQ_MMU_FREE_OBSOLETE_ROOTS \
@@ -1914,7 +1914,7 @@ struct kvm_x86_ops { 
	int (*enable_l2_tlb_flush)(struct kvm_vcpu *vcpu);



	void (*migrate_timers)(struct kvm_vcpu *vcpu);

	void (*recalc_msr_intercepts)(struct kvm_vcpu *vcpu);

	void (*recalc_intercepts)(struct kvm_vcpu *vcpu);

	int (*complete_emulated_msr)(struct kvm_vcpu *vcpu, int err);



	void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector);

arch/x86/kvm/svm/svm.c

+4 −4
Original line number Diff line number Diff line
@@ -1077,7 +1077,7 @@ static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu) 
	}

}



static void svm_recalc_intercepts_after_set_cpuid(struct kvm_vcpu *vcpu)

static void svm_recalc_intercepts(struct kvm_vcpu *vcpu)

{

	svm_recalc_instruction_intercepts(vcpu);

	svm_recalc_msr_intercepts(vcpu);
@@ -1225,7 +1225,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu) 


	svm_hv_init_vmcb(vmcb);



	svm_recalc_intercepts_after_set_cpuid(vcpu);

	svm_recalc_intercepts(vcpu);



	vmcb_mark_all_dirty(vmcb);
@@ -4479,7 +4479,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) 
	if (sev_guest(vcpu->kvm))

		sev_vcpu_after_set_cpuid(svm);



	svm_recalc_intercepts_after_set_cpuid(vcpu);

	svm_recalc_intercepts(vcpu);

}



static bool svm_has_wbinvd_exit(void)
@@ -5181,7 +5181,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { 


	.apic_init_signal_blocked = svm_apic_init_signal_blocked,



	.recalc_msr_intercepts = svm_recalc_msr_intercepts,

	.recalc_intercepts = svm_recalc_intercepts,

	.complete_emulated_msr = svm_complete_emulated_msr,



	.vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector,

arch/x86/kvm/vmx/main.c

+7 −7
Original line number Diff line number Diff line
@@ -188,18 +188,18 @@ static int vt_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
	return vmx_get_msr(vcpu, msr_info);

}



static void vt_recalc_msr_intercepts(struct kvm_vcpu *vcpu)

static void vt_recalc_intercepts(struct kvm_vcpu *vcpu)

{

	/*

	 * TDX doesn't allow VMM to configure interception of MSR accesses.

	 * TDX guest requests MSR accesses by calling TDVMCALL.  The MSR

	 * filters will be applied when handling the TDVMCALL for RDMSR/WRMSR

	 * if the userspace has set any.

	 * TDX doesn't allow VMM to configure interception of instructions or

	 * MSR accesses.  TDX guest requests MSR accesses by calling TDVMCALL.

	 * The MSR filters will be applied when handling the TDVMCALL for

	 * RDMSR/WRMSR if the userspace has set any.

	 */

	if (is_td_vcpu(vcpu))

		return;



	vmx_recalc_msr_intercepts(vcpu);

	vmx_recalc_intercepts(vcpu);

}



static int vt_complete_emulated_msr(struct kvm_vcpu *vcpu, int err)
@@ -995,7 +995,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = { 
	.apic_init_signal_blocked = vt_op(apic_init_signal_blocked),

	.migrate_timers = vmx_migrate_timers,



	.recalc_msr_intercepts = vt_op(recalc_msr_intercepts),

	.recalc_intercepts = vt_op(recalc_intercepts),

	.complete_emulated_msr = vt_op(complete_emulated_msr),



	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,

arch/x86/kvm/vmx/vmx.c

+7 −2
Original line number Diff line number Diff line
@@ -4068,7 +4068,7 @@ void pt_update_intercept_for_msr(struct kvm_vcpu *vcpu) 
	}

}



void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu)

static void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu)

{

	if (!cpu_has_vmx_msr_bitmap())

		return;
@@ -4121,6 +4121,11 @@ void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu) 
	 */

}



void vmx_recalc_intercepts(struct kvm_vcpu *vcpu)

{

	vmx_recalc_msr_intercepts(vcpu);

}



static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,

						int vector)

{
@@ -7802,7 +7807,7 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) 
			~FEAT_CTL_SGX_LC_ENABLED;



	/* Recalc MSR interception to account for feature changes. */

	vmx_recalc_msr_intercepts(vcpu);

	vmx_recalc_intercepts(vcpu);



	/* Refresh #PF interception to account for MAXPHYADDR changes. */

	vmx_update_exception_bitmap(vcpu);