[PATCH] KVM: X86: Reduce size of kvm_vcpu_arch structure when CONFIG_KVM_XEN=n

From: Hao Peng
Date: Mon Aug 21 2023 - 21:51:32 EST


From: Peng Hao <flyingpeng@xxxxxxxxxxx>

When CONFIG_KVM_XEN=n, the size of kvm_vcpu_arch can be reduced
from 5100+ to 4400+ by adding macro control.

Signed-off-by: Peng Hao <flyingpeng@xxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 5 ++++-
arch/x86/kvm/cpuid.c | 2 ++
arch/x86/kvm/x86.c | 2 ++
3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3bc146dfd38d..7e85016a8a0d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -680,6 +680,7 @@ struct kvm_hypervisor_cpuid {
u32 limit;
};

+#ifdef CONFIG_KVM_XEN
/* Xen HVM per vcpu emulation context */
struct kvm_vcpu_xen {
u64 hypercall_rip;
@@ -702,6 +703,7 @@ struct kvm_vcpu_xen {
struct timer_list poll_timer;
struct kvm_hypervisor_cpuid cpuid;
};
+#endif

struct kvm_queued_exception {
bool pending;
@@ -912,8 +914,9 @@ struct kvm_vcpu_arch {

bool hyperv_enabled;
struct kvm_vcpu_hv *hyperv;
+#ifdef CONFIG_KVM_XEN
struct kvm_vcpu_xen xen;
-
+#endif
cpumask_var_t wbinvd_dirty_mask;

unsigned long last_retry_eip;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7f4d13383cf2..f70a5e7db123 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -422,7 +422,9 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu,
struct kvm_cpuid_entry2 *e2,
vcpu->arch.cpuid_nent = nent;

vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
+#ifdef CONFIG_KVM_XEN
vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
+#endif
kvm_vcpu_after_set_cpuid(vcpu);

return 0;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 278dbd37dab2..f5238b2e6cb8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3231,11 +3231,13 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)

if (vcpu->pv_time.active)
kvm_setup_guest_pvclock(v, &vcpu->pv_time, 0);
+#ifdef CONFIG_KVM_XEN
if (vcpu->xen.vcpu_info_cache.active)
kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_info_cache,
offsetof(struct
compat_vcpu_info, time));
if (vcpu->xen.vcpu_time_info_cache.active)
kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_time_info_cache, 0);
+#endif
kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);
return 0;
}
--
2.31.1