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Subject[PART1 V5 13/13] svm: Manage vcpu load/unload when enable AVIC
Date
From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

When a vcpu is loaded/unloaded to a physical core, we need to update
host physical APIC ID information in the Physical APIC-ID table
accordingly.

Also, when vCPU is blocking/un-blocking (due to halt instruction),
we need to make sure that the is-running bit in set accordingly in the
physical APIC-ID table.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/svm.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 721e514..f903d33 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -35,6 +35,7 @@
#include <linux/trace_events.h>
#include <linux/slab.h>

+#include <asm/apic.h>
#include <asm/perf_event.h>
#include <asm/tlbflush.h>
#include <asm/desc.h>
@@ -183,6 +184,7 @@ struct vcpu_svm {
u32 ldr_reg;
struct page *avic_backing_page;
u64 *avic_physical_id_cache;
+ bool avic_is_blocking;
};

#define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK (0xFF)
@@ -1315,6 +1317,61 @@ free_avic:
return err;
}

+/**
+ * This function is called during VCPU halt/unhalt.
+ */
+static int avic_set_running(struct kvm_vcpu *vcpu, bool is_run)
+{
+ u64 entry;
+ int h_physical_id = __default_cpu_present_to_apicid(vcpu->cpu);
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (!kvm_vcpu_apicv_active(vcpu))
+ return 0;
+
+ /* ID = 0xff (broadcast), ID > 0xff (reserved) */
+ if (h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT)
+ return -EINVAL;
+
+ entry = READ_ONCE(*(svm->avic_physical_id_cache));
+ WARN_ON(is_run == !!(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK));
+
+ entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
+ if (is_run)
+ entry |= AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
+ WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
+
+ return 0;
+}
+
+static int avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu, bool is_load)
+{
+ u64 entry;
+ int h_physical_id = __default_cpu_present_to_apicid(cpu);
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (!kvm_vcpu_apicv_active(vcpu))
+ return 0;
+
+ /* ID = 0xff (broadcast), ID > 0xff (reserved) */
+ if (h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT)
+ return -EINVAL;
+
+ entry = READ_ONCE(*(svm->avic_physical_id_cache));
+ WARN_ON(is_load && (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK));
+
+ entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
+ if (is_load) {
+ entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
+ entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);
+ if (!svm->avic_is_blocking)
+ entry |= AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
+ }
+ WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
+
+ return 0;
+}
+
static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -1378,6 +1435,11 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
goto free_page4;
}

+ /* We initialize this flag to one to make sure that the is_running
+ * bit would be set the first time the vcpu is loaded.
+ */
+ svm->avic_is_blocking = false;
+
svm->nested.hsave = page_address(hsave_page);

svm->msrpm = page_address(msrpm_pages);
@@ -1454,6 +1516,8 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
/* This assumes that the kernel never uses MSR_TSC_AUX */
if (static_cpu_has(X86_FEATURE_RDTSCP))
wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
+
+ avic_vcpu_load(vcpu, cpu, true);
}

static void svm_vcpu_put(struct kvm_vcpu *vcpu)
@@ -1461,6 +1525,8 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
struct vcpu_svm *svm = to_svm(vcpu);
int i;

+ avic_vcpu_load(vcpu, 0, false);
+
++vcpu->stat.host_state_reload;
kvm_load_ldt(svm->host.ldt);
#ifdef CONFIG_X86_64
@@ -1476,6 +1542,18 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
}

+static void svm_vcpu_blocking(struct kvm_vcpu *vcpu)
+{
+ to_svm(vcpu)->avic_is_blocking = true;
+ avic_set_running(vcpu, false);
+}
+
+static void svm_vcpu_unblocking(struct kvm_vcpu *vcpu)
+{
+ to_svm(vcpu)->avic_is_blocking = false;
+ avic_set_running(vcpu, true);
+}
+
static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu)
{
return to_svm(vcpu)->vmcb->save.rflags;
@@ -4883,6 +4961,8 @@ static struct kvm_x86_ops svm_x86_ops = {
.prepare_guest_switch = svm_prepare_guest_switch,
.vcpu_load = svm_vcpu_load,
.vcpu_put = svm_vcpu_put,
+ .vcpu_blocking = svm_vcpu_blocking,
+ .vcpu_unblocking = svm_vcpu_unblocking,

.update_bp_intercept = update_bp_intercept,
.get_msr = svm_get_msr,
--
1.9.1
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