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Subject[RFC PATCH 5/8] svm: Add support for APIC_ACCESS_PAGE_PRIVATE_MEMSLOT setup/destroy
Date
Activate/deactivate AVIC requires setting/unsetting the memory region used
for 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.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/kvm/svm.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c33f02b4a19e..a23b1e77acb6 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1658,7 +1658,7 @@ 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;
@@ -1667,10 +1667,14 @@ static int avic_init_access_page(struct kvm_vcpu *vcpu)
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;

@@ -1680,6 +1684,26 @@ 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;
@@ -1687,7 +1711,7 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu)
int id = vcpu->vcpu_id;
struct vcpu_svm *svm = to_svm(vcpu);

- ret = avic_init_access_page(vcpu);
+ ret = avic_setup_access_page(vcpu, true);
if (ret)
return ret;

--
2.17.1
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