Activate/deactivate AVIC requires setting/unsetting the memory region used
for virtual APIC backing page (APIC_ACCESS_PAGE_PRIVATE_MEMSLOT).
So, re-factor avic_init_access_page() to avic_setup_access_page()
and add srcu_read_lock/unlock, which are needed to allow this function
to be called during run-time.

Also, introduce avic_destroy_access_page() to unset the page when
deactivate AVIC.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
---
 arch/x86/kvm/svm.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 47 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8673617..2e06ee2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1476,7 +1476,9 @@ static u64 svm_write_l1_tsc_offset(struct kvm_vcpu *vcpu, 
u64 offset)
 static void avic_init_vmcb(struct vcpu_svm *svm)
 {
        struct vmcb *vmcb = svm->vmcb;
-       struct kvm_svm *kvm_svm = to_kvm_svm(svm->vcpu.kvm);
+       struct kvm *kvm = svm->vcpu.kvm;
+       struct kvm_svm *kvm_svm = to_kvm_svm(kvm);
+
        phys_addr_t bpa = __sme_set(page_to_phys(svm->avic_backing_page));
        phys_addr_t lpa = 
__sme_set(page_to_phys(kvm_svm->avic_logical_id_table_page));
        phys_addr_t ppa = 
__sme_set(page_to_phys(kvm_svm->avic_physical_id_table_page));
@@ -1485,7 +1487,13 @@ static void avic_init_vmcb(struct vcpu_svm *svm)
        vmcb->control.avic_logical_id = lpa & AVIC_HPA_MASK;
        vmcb->control.avic_physical_id = ppa & AVIC_HPA_MASK;
        vmcb->control.avic_physical_id |= AVIC_MAX_PHYSICAL_ID_COUNT;
-       vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
+
+       mutex_lock(&kvm->arch.apicv_lock);
+       if (kvm->arch.apicv_state == APICV_ACTIVATED)
+               vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
+       else
+               vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
+       mutex_unlock(&kvm->arch.apicv_lock);
 }
 
 static void init_vmcb(struct vcpu_svm *svm)
@@ -1668,19 +1676,24 @@ static u64 *avic_get_physical_id_entry(struct kvm_vcpu 
*vcpu,
  * field of the VMCB. Therefore, we set up the
  * APIC_ACCESS_PAGE_PRIVATE_MEMSLOT (4KB) here.
  */
-static int avic_init_access_page(struct kvm_vcpu *vcpu)
+static int avic_setup_access_page(struct kvm_vcpu *vcpu, bool init)
 {
        struct kvm *kvm = vcpu->kvm;
        int ret = 0;
 
        mutex_lock(&kvm->slots_lock);
+
        if (kvm->arch.apic_access_page_done)
                goto out;
 
+       if (!init)
+               srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
        ret = __x86_set_memory_region(kvm,
                                      APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
                                      APIC_DEFAULT_PHYS_BASE,
                                      PAGE_SIZE);
+       if (!init)
+               vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
        if (ret)
                goto out;
 
@@ -1690,14 +1703,39 @@ static int avic_init_access_page(struct kvm_vcpu *vcpu)
        return ret;
 }
 
+static void avic_destroy_access_page(struct kvm_vcpu *vcpu)
+{
+       struct kvm *kvm = vcpu->kvm;
+
+       mutex_lock(&kvm->slots_lock);
+
+       if (!kvm->arch.apic_access_page_done)
+               goto out;
+
+       srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
+       __x86_set_memory_region(kvm,
+                               APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
+                               APIC_DEFAULT_PHYS_BASE,
+                               0);
+       vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
+       kvm->arch.apic_access_page_done = false;
+out:
+       mutex_unlock(&kvm->slots_lock);
+}
+
 static int avic_init_backing_page(struct kvm_vcpu *vcpu)
 {
-       int ret;
+       int ret = 0;
        u64 *entry, new_entry;
        int id = vcpu->vcpu_id;
+       struct kvm *kvm = vcpu->kvm;
        struct vcpu_svm *svm = to_svm(vcpu);
 
-       ret = avic_init_access_page(vcpu);
+       mutex_lock(&kvm->arch.apicv_lock);
+       if (kvm->arch.apicv_state == APICV_ACTIVATED)
+               ret = avic_setup_access_page(vcpu, true);
+       mutex_unlock(&kvm->arch.apicv_lock);
+
        if (ret)
                return ret;
 
@@ -2187,7 +2225,10 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, 
unsigned int id)
        /* We initialize this flag to true to make sure that the is_running
         * bit would be set the first time the vcpu is loaded.
         */
-       svm->avic_is_running = true;
+       mutex_lock(&kvm->arch.apicv_lock);
+       if (irqchip_in_kernel(kvm) && kvm->arch.apicv_state == APICV_ACTIVATED)
+               svm->avic_is_running = true;
+       mutex_unlock(&kvm->arch.apicv_lock);
 
        svm->nested.hsave = page_address(hsave_page);
 
-- 
1.8.3.1

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