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authorSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>2019-11-14 23:15:16 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2020-02-05 17:17:44 +0300
commite2ed4078a6ef3ddf4063329298852e24c36d46c8 (patch)
treecdd5efeedb8adb92c7ca4177589065bdd3056954 /arch
parentf3515dc3bef81e96bdb2ac93ef8fd20b1c2aaae5 (diff)
downloadlinux-e2ed4078a6ef3ddf4063329298852e24c36d46c8.tar.xz
kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection mode.
AMD SVM AVIC accelerates EOI write and does not trap. This causes in-kernel PIT re-injection mode to fail since it relies on irq-ack notifier mechanism. So, APICv is activated only when in-kernel PIT is in discard mode e.g. w/ qemu option: -global kvm-pit.lost_tick_policy=discard Also, introduce APICV_INHIBIT_REASON_PIT_REINJ bit to be used for this reason. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/kvm_host.h1
-rw-r--r--arch/x86/kvm/i8254.c12
-rw-r--r--arch/x86/kvm/svm.c11
3 files changed, 22 insertions, 2 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2bd7fd96d994..4dffbc10d3f8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -879,6 +879,7 @@ enum kvm_irqchip_mode {
#define APICV_INHIBIT_REASON_HYPERV 1
#define APICV_INHIBIT_REASON_NESTED 2
#define APICV_INHIBIT_REASON_IRQWIN 3
+#define APICV_INHIBIT_REASON_PIT_REINJ 4
struct kvm_arch {
unsigned long n_used_mmu_pages;
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4a6dc54cc12b..b24c606ac04b 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -295,12 +295,24 @@ void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject)
if (atomic_read(&ps->reinject) == reinject)
return;
+ /*
+ * AMD SVM AVIC accelerates EOI write and does not trap.
+ * This cause in-kernel PIT re-inject mode to fail
+ * since it checks ps->irq_ack before kvm_set_irq()
+ * and relies on the ack notifier to timely queue
+ * the pt->worker work iterm and reinject the missed tick.
+ * So, deactivate APICv when PIT is in reinject mode.
+ */
if (reinject) {
+ kvm_request_apicv_update(kvm, false,
+ APICV_INHIBIT_REASON_PIT_REINJ);
/* The initial state is preserved while ps->reinject == 0. */
kvm_pit_reset_reinject(pit);
kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
} else {
+ kvm_request_apicv_update(kvm, true,
+ APICV_INHIBIT_REASON_PIT_REINJ);
kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
}
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 6d300c16d756..0b05967aa455 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1739,7 +1739,13 @@ static int avic_update_access_page(struct kvm *kvm, bool activate)
int ret = 0;
mutex_lock(&kvm->slots_lock);
- if (kvm->arch.apic_access_page_done == activate)
+ /*
+ * During kvm_destroy_vm(), kvm_pit_set_reinject() could trigger
+ * APICv mode change, which update APIC_ACCESS_PAGE_PRIVATE_MEMSLOT
+ * memory region. So, we need to ensure that kvm->mm == current->mm.
+ */
+ if ((kvm->arch.apic_access_page_done == activate) ||
+ (kvm->mm != current->mm))
goto out;
ret = __x86_set_memory_region(kvm,
@@ -7353,7 +7359,8 @@ static bool svm_check_apicv_inhibit_reasons(ulong bit)
ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
BIT(APICV_INHIBIT_REASON_HYPERV) |
BIT(APICV_INHIBIT_REASON_NESTED) |
- BIT(APICV_INHIBIT_REASON_IRQWIN);
+ BIT(APICV_INHIBIT_REASON_IRQWIN) |
+ BIT(APICV_INHIBIT_REASON_PIT_REINJ);
return supported & BIT(bit);
}