Commit 06692e4b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: VMX: Move RESET emulation to vmx_vcpu_reset() 



Move vCPU RESET emulation, including initializating of select VMCS state,
to vmx_vcpu_reset().  Drop the open coded "vCPU load" sequence, as
->vcpu_reset() is invoked while the vCPU is properly loaded (which is
kind of the point of ->vcpu_reset()...).  Hopefully KVM will someday
expose a dedicated RESET ioctl(), and in the meantime separating "create"
from "RESET" is a nice cleanup.

Deferring VMCS initialization is effectively a nop as it's impossible to
safely access the VMCS between the current call site and its new home, as
both the vCPU and the pCPU are put immediately after init_vmcs(), i.e.
the VMCS isn't guaranteed to be loaded.

Note, task preemption is not a problem as vmx_sched_in() _can't_ touch
the VMCS as ->sched_in() is invoked before the vCPU, and thus VMCS, is
reloaded.  I.e. the preemption path also can't consume VMCS state.

Cc: Reiji Watanabe <reijiw@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210921000303.400537-9-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d0656735

arch/x86/kvm/vmx/vmx.c

+32 −31
Original line number Diff line number Diff line
@@ -4328,10 +4328,6 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx) 


#define VMX_XSS_EXIT_BITMAP 0



/*

 * Noting that the initialization of Guest-state Area of VMCS is in

 * vmx_vcpu_reset().

 */

static void init_vmcs(struct vcpu_vmx *vmx)

{

	if (nested)
@@ -4436,10 +4432,40 @@ static void init_vmcs(struct vcpu_vmx *vmx) 
	vmx_setup_uret_msrs(vmx);

}



static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);



	init_vmcs(vmx);



	if (nested)

		memcpy(&vmx->nested.msrs, &vmcs_config.nested, sizeof(vmx->nested.msrs));



	vcpu_setup_sgx_lepubkeyhash(vcpu);



	vmx->nested.posted_intr_nv = -1;

	vmx->nested.vmxon_ptr = INVALID_GPA;

	vmx->nested.current_vmptr = INVALID_GPA;

	vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;



	vcpu->arch.microcode_version = 0x100000000ULL;

	vmx->msr_ia32_feature_control_valid_bits = FEAT_CTL_LOCKED;



	/*

	 * Enforce invariant: pi_desc.nv is always either POSTED_INTR_VECTOR

	 * or POSTED_INTR_WAKEUP_VECTOR.

	 */

	vmx->pi_desc.nv = POSTED_INTR_VECTOR;

	vmx->pi_desc.sn = 1;

}



static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);



	if (!init_event)

		__vmx_vcpu_reset(vcpu);



	vmx->rmode.vm86_active = 0;

	vmx->spec_ctrl = 0;
@@ -6816,7 +6842,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) 
{

	struct vmx_uret_msr *tsx_ctrl;

	struct vcpu_vmx *vmx;

	int i, cpu, err;

	int i, err;



	BUILD_BUG_ON(offsetof(struct vcpu_vmx, vcpu) != 0);

	vmx = to_vmx(vcpu);
@@ -6875,12 +6901,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) 
	}



	vmx->loaded_vmcs = &vmx->vmcs01;

	cpu = get_cpu();

	vmx_vcpu_load(vcpu, cpu);

	vcpu->cpu = cpu;

	init_vmcs(vmx);

	vmx_vcpu_put(vcpu);

	put_cpu();



	if (cpu_need_virtualize_apic_accesses(vcpu)) {

		err = alloc_apic_access_page(vcpu->kvm);

		if (err)
@@ -6893,26 +6914,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) 
			goto free_vmcs;

	}



	if (nested)

		memcpy(&vmx->nested.msrs, &vmcs_config.nested, sizeof(vmx->nested.msrs));



	vcpu_setup_sgx_lepubkeyhash(vcpu);



	vmx->nested.posted_intr_nv = -1;

	vmx->nested.vmxon_ptr = INVALID_GPA;

	vmx->nested.current_vmptr = INVALID_GPA;

	vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;



	vcpu->arch.microcode_version = 0x100000000ULL;

	vmx->msr_ia32_feature_control_valid_bits = FEAT_CTL_LOCKED;



	/*

	 * Enforce invariant: pi_desc.nv is always either POSTED_INTR_VECTOR

	 * or POSTED_INTR_WAKEUP_VECTOR.

	 */

	vmx->pi_desc.nv = POSTED_INTR_VECTOR;

	vmx->pi_desc.sn = 1;



	return 0;



free_vmcs: