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KVM: x86: Allocate vcpu struct in common x86 code
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Move allocation of VMX and SVM vcpus to common x86.  Although the struct
being allocated is technically a VMX/SVM struct, it can be interpreted
directly as a 'struct kvm_vcpu' because of the pre-existing requirement
that 'struct kvm_vcpu' be located at offset zero of the arch/vendor vcpu
struct.

Remove the message from the build-time assertions regarding placement of
the struct, as compatibility with the arch usercopy region is no longer
the sole dependent on 'struct kvm_vcpu' being at offset zero.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Sean Christopherson authored and Paolo Bonzini committed Jan 24, 2020
1 parent 7f27179 commit a9dd6f0
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Showing 4 changed files with 30 additions and 40 deletions.
2 changes: 1 addition & 1 deletion arch/x86/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1050,7 +1050,7 @@ struct kvm_x86_ops {
void (*vm_destroy)(struct kvm *kvm);

/* Create, but do not attach this VCPU */
struct kvm_vcpu *(*vcpu_create)(struct kvm *kvm, unsigned id);
int (*vcpu_create)(struct kvm *kvm, struct kvm_vcpu *vcpu, unsigned id);
void (*vcpu_free)(struct kvm_vcpu *vcpu);
void (*vcpu_reset)(struct kvm_vcpu *vcpu, bool init_event);

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28 changes: 9 additions & 19 deletions arch/x86/kvm/svm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2187,32 +2187,25 @@ static int avic_init_vcpu(struct vcpu_svm *svm)
return ret;
}

static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
static int svm_create_vcpu(struct kvm *kvm, struct kvm_vcpu *vcpu,
unsigned int id)
{
struct kvm_vcpu *vcpu;
struct vcpu_svm *svm;
struct page *page;
struct page *msrpm_pages;
struct page *hsave_page;
struct page *nested_msrpm_pages;
int err;

BUILD_BUG_ON_MSG(offsetof(struct vcpu_svm, vcpu) != 0,
"struct kvm_vcpu must be at offset 0 for arch usercopy region");

svm = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT);
if (!svm) {
err = -ENOMEM;
goto out;
}
vcpu = &svm->vcpu;
BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
svm = to_svm(vcpu);

vcpu->arch.user_fpu = kmem_cache_zalloc(x86_fpu_cache,
GFP_KERNEL_ACCOUNT);
if (!vcpu->arch.user_fpu) {
printk(KERN_ERR "kvm: failed to allocate kvm userspace's fpu\n");
err = -ENOMEM;
goto free_partial_svm;
goto out;
}

vcpu->arch.guest_fpu = kmem_cache_zalloc(x86_fpu_cache,
Expand All @@ -2225,7 +2218,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)

err = kvm_vcpu_init(vcpu, kvm, id);
if (err)
goto free_svm;
goto free_guest_fpu;

err = -ENOMEM;
page = alloc_page(GFP_KERNEL_ACCOUNT);
Expand Down Expand Up @@ -2269,7 +2262,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)

svm_init_osvw(vcpu);

return vcpu;
return 0;

free_page4:
__free_page(hsave_page);
Expand All @@ -2281,14 +2274,12 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
__free_page(page);
uninit:
kvm_vcpu_uninit(vcpu);
free_svm:
free_guest_fpu:
kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
free_user_fpu:
kmem_cache_free(x86_fpu_cache, vcpu->arch.user_fpu);
free_partial_svm:
kmem_cache_free(kvm_vcpu_cache, svm);
out:
return ERR_PTR(err);
return err;
}

static void svm_clear_current_vmcb(struct vmcb *vmcb)
Expand Down Expand Up @@ -2317,7 +2308,6 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
kvm_vcpu_uninit(vcpu);
kmem_cache_free(x86_fpu_cache, vcpu->arch.user_fpu);
kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
kmem_cache_free(kvm_vcpu_cache, svm);
}

static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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24 changes: 8 additions & 16 deletions arch/x86/kvm/vmx/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6684,31 +6684,24 @@ static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
kvm_vcpu_uninit(vcpu);
kmem_cache_free(x86_fpu_cache, vcpu->arch.user_fpu);
kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
kmem_cache_free(kvm_vcpu_cache, vmx);
}

static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
static int vmx_create_vcpu(struct kvm *kvm, struct kvm_vcpu *vcpu,
unsigned int id)
{
struct kvm_vcpu *vcpu;
struct vcpu_vmx *vmx;
unsigned long *msr_bitmap;
int i, cpu, err;

BUILD_BUG_ON_MSG(offsetof(struct vcpu_vmx, vcpu) != 0,
"struct kvm_vcpu must be at offset 0 for arch usercopy region");

vmx = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT);
if (!vmx)
return ERR_PTR(-ENOMEM);

vcpu = &vmx->vcpu;
BUILD_BUG_ON(offsetof(struct vcpu_vmx, vcpu) != 0);
vmx = to_vmx(vcpu);

vcpu->arch.user_fpu = kmem_cache_zalloc(x86_fpu_cache,
GFP_KERNEL_ACCOUNT);
if (!vcpu->arch.user_fpu) {
printk(KERN_ERR "kvm: failed to allocate kvm userspace's fpu\n");
err = -ENOMEM;
goto free_partial_vcpu;
goto out;
}

vcpu->arch.guest_fpu = kmem_cache_zalloc(x86_fpu_cache,
Expand Down Expand Up @@ -6829,7 +6822,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)

vmx->ept_pointer = INVALID_PAGE;

return vcpu;
return 0;

free_vmcs:
free_loaded_vmcs(vmx->loaded_vmcs);
Expand All @@ -6842,9 +6835,8 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
free_user_fpu:
kmem_cache_free(x86_fpu_cache, vcpu->arch.user_fpu);
free_partial_vcpu:
kmem_cache_free(kvm_vcpu_cache, vmx);
return ERR_PTR(err);
out:
return err;
}

#define L1TF_MSG_SMT "L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.\n"
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16 changes: 12 additions & 4 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9172,26 +9172,34 @@ static void fx_init(struct kvm_vcpu *vcpu)

void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
{
void *wbinvd_dirty_mask = vcpu->arch.wbinvd_dirty_mask;

kvmclock_reset(vcpu);

kvm_x86_ops->vcpu_free(vcpu);
free_cpumask_var(wbinvd_dirty_mask);

free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);
kmem_cache_free(kvm_vcpu_cache, vcpu);
}

struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
unsigned int id)
{
struct kvm_vcpu *vcpu;
int r;

if (kvm_check_tsc_unstable() && atomic_read(&kvm->online_vcpus) != 0)
printk_once(KERN_WARNING
"kvm: SMP vm created on host with unstable TSC; "
"guest TSC will not be reliable\n");

vcpu = kvm_x86_ops->vcpu_create(kvm, id);
vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT);
if (!vcpu)
return ERR_PTR(-ENOMEM);

r = kvm_x86_ops->vcpu_create(kvm, vcpu, id);
if (r) {
kmem_cache_free(kvm_vcpu_cache, vcpu);
return ERR_PTR(r);
}
return vcpu;
}

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