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KVM: VMX: Move RESET emulation to vmx_vcpu_reset()

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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: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210921000303.400537-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-09-20 17:03:01 -07:00 committed by Paolo Bonzini
parent d06567353e
commit 06692e4b80
1 changed files with 32 additions and 31 deletions
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63
arch/x86/kvm/vmx/vmx.c
View File

@ -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: