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KVM: x86: hyper-v: Allocate 'struct kvm_vcpu_hv' dynamically

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Hyper-V context is only needed for guests which use Hyper-V emulation in
KVM (e.g. Windows/Hyper-V guests). 'struct kvm_vcpu_hv' is, however, quite
big, it accounts for more than 1/4 of the total 'struct kvm_vcpu_arch'
which is also quite big already. This all looks like a waste.

Allocate 'struct kvm_vcpu_hv' dynamically. This patch does not bring any
(intentional) functional change as we still allocate the context
unconditionally but it paves the way to doing that only when needed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-13-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2021-01-26 14:48:13 +01:00 committed by Paolo Bonzini
parent f2bc14b69c
commit 4592b7eaa8
4 changed files with 27 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/include/asm/kvm_host.h
View File

@ -519,6 +519,7 @@ struct kvm_vcpu_hv_synic {
/* Hyper-V per vcpu emulation context */
struct kvm_vcpu_hv {
struct kvm_vcpu *vcpu;
u32 vp_index;
u64 hv_vapic;
s64 runtime_offset;
@ -735,7 +736,7 @@ struct kvm_vcpu_arch {
/* used for guest single stepping over the given code position */
unsigned long singlestep_rip;
struct kvm_vcpu_hv hyperv;
struct kvm_vcpu_hv *hyperv;
struct kvm_vcpu_xen xen;
cpumask_var_t wbinvd_dirty_mask;

16
arch/x86/kvm/hyperv.c
View File

@ -837,6 +837,9 @@ void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu)
for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++)
stimer_cleanup(&hv_vcpu->stimer[i]);
kfree(hv_vcpu);
vcpu->arch.hyperv = NULL;
}
bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu)
@ -886,16 +889,25 @@ static void stimer_init(struct kvm_vcpu_hv_stimer *stimer, int timer_index)
stimer_prepare_msg(stimer);
}
void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
struct kvm_vcpu_hv *hv_vcpu;
int i;
hv_vcpu = kzalloc(sizeof(struct kvm_vcpu_hv), GFP_KERNEL_ACCOUNT);
if (!hv_vcpu)
return -ENOMEM;
vcpu->arch.hyperv = hv_vcpu;
hv_vcpu->vcpu = vcpu;
synic_init(&hv_vcpu->synic);
bitmap_zero(hv_vcpu->stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);
for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++)
stimer_init(&hv_vcpu->stimer[i], i);
return 0;
}
void kvm_hv_vcpu_postcreate(struct kvm_vcpu *vcpu)

13
arch/x86/kvm/hyperv.h
View File

@ -57,20 +57,19 @@ static inline struct kvm_hv *to_kvm_hv(struct kvm *kvm)
static inline struct kvm_vcpu_hv *to_hv_vcpu(struct kvm_vcpu *vcpu)
{
return &vcpu->arch.hyperv;
return vcpu->arch.hyperv;
}
static inline struct kvm_vcpu *hv_vcpu_to_vcpu(struct kvm_vcpu_hv *hv_vcpu)
{
struct kvm_vcpu_arch *arch;
arch = container_of(hv_vcpu, struct kvm_vcpu_arch, hyperv);
return container_of(arch, struct kvm_vcpu, arch);
return hv_vcpu->vcpu;
}
static inline struct kvm_vcpu_hv_synic *to_hv_synic(struct kvm_vcpu *vcpu)
{
return &vcpu->arch.hyperv.synic;
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
return &hv_vcpu->synic;
}
static inline struct kvm_vcpu *hv_synic_to_vcpu(struct kvm_vcpu_hv_synic *synic)
@ -101,7 +100,7 @@ int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint);
void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector);
int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages);
void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu);
int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu);
void kvm_hv_vcpu_postcreate(struct kvm_vcpu *vcpu);
void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu);

7
arch/x86/kvm/x86.c
View File

@ -10083,11 +10083,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.pending_external_vector = -1;
vcpu->arch.preempted_in_kernel = false;
kvm_hv_vcpu_init(vcpu);
if (kvm_hv_vcpu_init(vcpu))
goto free_guest_fpu;
r = static_call(kvm_x86_vcpu_create)(vcpu);
if (r)
goto free_guest_fpu;
goto free_hv_vcpu;
vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();
vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
@ -10098,6 +10099,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu_put(vcpu);
return 0;
free_hv_vcpu:
kvm_hv_vcpu_uninit(vcpu);
free_guest_fpu:
kvm_free_guest_fpu(vcpu);
free_user_fpu: