[PART1 RFC v3 06/12] KVM: x86: Detect and Initialize AVIC support

Suravee Suthikulpanit
2016-03-18T06:11:31Z

This patch introduces AVIC-related data structure, and AVIC
initialization code.

There are three main data structures for AVIC:
* Virtual APIC (vAPIC) backing page (per-VCPU)
* Physical APIC ID table (per-VM)
* Logical APIC ID table (per-VM)

Currently, AVIC is disabled by default. Users can manually
enable AVIC via kernel boot option kvm-amd.avic=1 or during
kvm-amd module loading with parameter avic=1.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/include/asm/kvm_host.h | 8 ++
arch/x86/include/asm/svm.h | 3 +
arch/x86/kvm/svm.c | 232 +++++++++++++++++++++++++++++++++++++++-
3 files changed, 242 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 87eac2a..2698e40 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -754,6 +754,14 @@ struct kvm_arch {

bool irqchip_split;
u8 nr_reserved_ioapic_pins;
+
+ /* Struct members for AVIC */
+ struct hlist_node hnode;
+ struct kvm *kvm;
+ u32 ldr_mode;
+ u32 avic_tag;
+ struct page *avic_log_apic_id_table_page;
+ struct page *avic_phy_apic_id_table_page;
};

struct kvm_vm_stat {
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 66e26a0..287e635 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -116,6 +116,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define V_INTR_MASKING_SHIFT 24
#define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)

+#define AVIC_ENABLE_SHIFT 31
+#define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)
+
#define SVM_INTERRUPT_SHADOW_MASK 1

#define SVM_IOIO_STR_SHIFT 2
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c13a64b..621c948 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -14,6 +14,9 @@
* the COPYING file in the top-level directory.
*
*/
+
+#define pr_fmt(fmt) "SVM: " fmt
+
#include <linux/kvm_host.h>

#include "irq.h"
@@ -78,6 +81,11 @@ MODULE_DEVICE_TABLE(x86cpu, svm_cpu_id);
#define TSC_RATIO_MIN 0x0000000000000001ULL
#define TSC_RATIO_MAX 0x000000ffffffffffULL

+#define AVIC_HPA_MASK ~((0xFFFULL << 52) || 0xFFF)
+
+/* NOTE: Current max index allowed for physical APIC ID table is 255 */
+#define AVIC_PHY_APIC_ID_MAX 0xFF
+
static bool erratum_383_found __read_mostly;

static const u32 host_save_user_msrs[] = {
@@ -162,8 +170,20 @@ struct vcpu_svm {

/* cached guest cpuid flags for faster access */
bool nrips_enabled : 1;
+
+ struct page *avic_backing_page;
+ u64 *avic_phy_apic_id_cache;
+ bool avic_was_running;
};

+#define AVIC_LOG_APIC_ID__GUEST_PHY_APIC_ID_MSK (0xFF)
+#define AVIC_LOG_APIC_ID__VALID_MSK (1 << 31)
+
+#define AVIC_PHY_APIC_ID__HOST_PHY_APIC_ID_MSK (0xFFULL)
+#define AVIC_PHY_APIC_ID__BACKING_PAGE_MSK (0xFFFFFFFFFFULL << 12)
+#define AVIC_PHY_APIC_ID__IS_RUN_MSK (1ULL << 62)
+#define AVIC_PHY_APIC_ID__VALID_MSK (1ULL << 63)
+
static DEFINE_PER_CPU(u64, current_tsc_ratio);
#define TSC_RATIO_DEFAULT 0x0100000000ULL

@@ -205,6 +225,10 @@ module_param(npt, int, S_IRUGO);
static int nested = true;
module_param(nested, int, S_IRUGO);

+/* enable / disable AVIC */
+static int avic;
+module_param(avic, int, S_IRUGO);
+
static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
static void svm_flush_tlb(struct kvm_vcpu *vcpu);
static void svm_complete_interrupts(struct vcpu_svm *svm);
@@ -234,6 +258,18 @@ enum {
/* TPR and CR2 are always written before VMRUN */
#define VMCB_ALWAYS_DIRTY_MASK ((1U << VMCB_INTR) | (1U << VMCB_CR2))

+#define VMCB_AVIC_APIC_BAR_MASK 0xFFFFFFFFFF000ULL
+
+static inline bool svm_vcpu_avic_enabled(struct vcpu_svm *svm)
+{
+ return (avic && (svm->vmcb->control.int_ctl & AVIC_ENABLE_MASK));
+}
+
+static inline void avic_update_vapic_bar(struct vcpu_svm *svm, u64 data)
+{
+ svm->vmcb->control.avic_vapic_bar = data & VMCB_AVIC_APIC_BAR_MASK;
+}
+
static inline void mark_all_dirty(struct vmcb *vmcb)
{
vmcb->control.clean = 0;
@@ -923,6 +959,13 @@ static __init int svm_hardware_setup(void)
} else
kvm_disable_tdp();

+ if (avic && (!npt_enabled || !boot_cpu_has(X86_FEATURE_AVIC)))
+ avic = false;
+
+ if (avic) {
+ printk(KERN_INFO "kvm: AVIC enabled\n");
+ }
+
return 0;

err:
@@ -1000,6 +1043,24 @@ static void svm_adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, s64 adjustment)
mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
}

+static void avic_init_vmcb(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = svm->vmcb;
+ struct kvm_arch *vm_data = &svm->vcpu.kvm->arch;
+ phys_addr_t bpa = page_to_phys(svm->avic_backing_page);
+ phys_addr_t lpa = page_to_phys(vm_data->avic_log_apic_id_table_page);
+ phys_addr_t ppa = page_to_phys(vm_data->avic_phy_apic_id_table_page);
+
+ if (!vmcb)
+ return;
+
+ vmcb->control.avic_backing_page = bpa & AVIC_HPA_MASK;
+ vmcb->control.avic_log_apic_id = lpa & AVIC_HPA_MASK;
+ vmcb->control.avic_phy_apic_id = ppa & AVIC_HPA_MASK;
+ vmcb->control.avic_phy_apic_id |= AVIC_PHY_APIC_ID_MAX;
+ vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
+}
+
static void init_vmcb(struct vcpu_svm *svm)
{
struct vmcb_control_area *control = &svm->vmcb->control;
@@ -1113,6 +1174,139 @@ static void init_vmcb(struct vcpu_svm *svm)
mark_all_dirty(svm->vmcb);

enable_gif(svm);
+
+ if (avic)
+ avic_init_vmcb(svm);
+}
+
+static u64 *avic_get_phy_apic_id_entry(struct kvm_vcpu *vcpu, int index)
+{
+ u64 *avic_phy_ait;
+ struct kvm_arch *vm_data = &vcpu->kvm->arch;
+
+ /* Note: APIC ID = 0xff is used for broadcast.
+ * APIC ID > 0xff is reserved.
+ */
+ if (index >= 0xff)
+ return NULL;
+
+ avic_phy_ait = page_address(vm_data->avic_phy_apic_id_table_page);
+
+ return &avic_phy_ait[index];
+}
+
+static int avic_init_backing_page(struct kvm_vcpu *vcpu)
+{
+ u64 *entry, new_entry;
+ int id = vcpu->vcpu_id;
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (id >= AVIC_PHY_APIC_ID_MAX)
+ return -EINVAL;
+
+ if (!svm->vcpu.arch.apic->regs)
+ return -EINVAL;
+
+ svm->avic_backing_page = virt_to_page(svm->vcpu.arch.apic->regs);
+
+ avic_init_vmcb(svm);
+
+ /* Setting AVIC backing page address in the phy APIC ID table */
+ entry = avic_get_phy_apic_id_entry(vcpu, id);
+ if (!entry)
+ return -EINVAL;
+
+ new_entry = READ_ONCE(*entry);
+ new_entry = (page_to_phys(svm->avic_backing_page) &
+ AVIC_PHY_APIC_ID__BACKING_PAGE_MSK) |
+ AVIC_PHY_APIC_ID__VALID_MSK;
+ WRITE_ONCE(*entry, new_entry);
+
+ svm->avic_phy_apic_id_cache = entry;
+
+ return 0;
+}
+
+static void avic_vm_uninit(struct kvm *kvm)
+{
+ unsigned long flags;
+ struct kvm_arch *vm_data = &kvm->arch;
+
+ if (vm_data->avic_log_apic_id_table_page)
+ __free_page(vm_data->avic_log_apic_id_table_page);
+ if (vm_data->avic_phy_apic_id_table_page)
+ __free_page(vm_data->avic_phy_apic_id_table_page);
+}
+
+static void avic_vcpu_uninit(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (!avic)
+ return;
+
+ if (svm->avic_phy_apic_id_cache)
+ svm->avic_phy_apic_id_cache = NULL;
+}
+
+static atomic_t avic_tag_gen = ATOMIC_INIT(1);
+
+static inline u32 avic_get_next_tag(void)
+{
+ u32 tag = atomic_read(&avic_tag_gen);
+
+ atomic_inc(&avic_tag_gen);
+ return tag;
+}
+
+static int avic_vm_init(struct kvm *kvm)
+{
+ int err = -ENOMEM;
+ struct kvm_arch *vm_data = &kvm->arch;
+ struct page *p_page;
+ struct page *l_page;
+
+ /**
+ * Note:
+ * AVIC hardware walks the nested page table to check permissions,
+ * but does not use the SPA address specified in the leaf page
+ * table entry since it uses address in the AVIC_BACKING_PAGE pointer
+ * field of the VMCB. Therefore, we set up the
+ * APIC_ACCESS_PAGE_PRIVATE_MEMSLOT (4KB) here.
+ */
+ mutex_lock(&kvm->slots_lock);
+ err = __x86_set_memory_region(kvm,
+ APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
+ APIC_DEFAULT_PHYS_BASE,
+ PAGE_SIZE);
+ mutex_unlock(&kvm->slots_lock);
+ if (err)
+ goto free_avic;
+ kvm->arch.apic_access_page_done = true;
+
+ /* Allocating physical APIC ID table (4KB) */
+ p_page = alloc_page(GFP_KERNEL);
+ if (!p_page)
+ goto free_avic;
+
+ vm_data->avic_phy_apic_id_table_page = p_page;
+ clear_page(page_address(p_page));
+
+ /* Allocating logical APIC ID table (4KB) */
+ l_page = alloc_page(GFP_KERNEL);
+ if (!l_page)
+ goto free_avic;
+
+ vm_data->avic_log_apic_id_table_page = l_page;
+ clear_page(page_address(l_page));
+
+ vm_data->avic_tag = avic_get_next_tag();
+
+ return 0;
+
+free_avic:
+ avic_vm_uninit(kvm);
+ return err;
}

static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -1131,6 +1325,9 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)

kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy);
kvm_register_write(vcpu, VCPU_REGS_RDX, eax);
+
+ if (svm_vcpu_avic_enabled(svm) && !init_event)
+ avic_update_vapic_bar(svm, APIC_DEFAULT_PHYS_BASE);
}

static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
@@ -1169,6 +1366,14 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
if (!hsave_page)
goto free_page3;

+ if (avic) {
+ err = avic_init_backing_page(&svm->vcpu);
+ if (err) {
+ avic_vcpu_uninit(&svm->vcpu);
+ goto free_page4;
+ }
+ }
+
svm->nested.hsave = page_address(hsave_page);

svm->msrpm = page_address(msrpm_pages);
@@ -1187,6 +1392,8 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)

return &svm->vcpu;

+free_page4:
+ __free_page(hsave_page);
free_page3:
__free_pages(nested_msrpm_pages, MSRPM_ALLOC_ORDER);
free_page2:
@@ -1209,6 +1416,7 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
__free_page(virt_to_page(svm->nested.hsave));
__free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
+ avic_vcpu_uninit(vcpu);
kvm_vcpu_uninit(vcpu);
kmem_cache_free(kvm_vcpu_cache, svm);
}
@@ -3371,6 +3579,7 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
pr_err("%-20s%08x\n", "exit_int_info_err:", control->exit_int_info_err);
pr_err("%-20s%lld\n", "nested_ctl:", control->nested_ctl);
pr_err("%-20s%016llx\n", "nested_cr3:", control->nested_cr3);
+ pr_err("%-20s%016llx\n", "avic_vapic_bar:", control->avic_vapic_bar);
pr_err("%-20s%08x\n", "event_inj:", control->event_inj);
pr_err("%-20s%08x\n", "event_inj_err:", control->event_inj_err);
pr_err("%-20s%lld\n", "lbr_ctl:", control->lbr_ctl);
@@ -3602,11 +3811,27 @@ static void svm_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)

static bool svm_get_enable_apicv(void)
{
- return false;
+ return avic;
}

+static void svm_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
+{
+}
+
+static void svm_hwapic_isr_update(struct kvm *kvm, int isr)
+{
+}
+
+/* Note: Currently only used by Hyper-V. */
static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ struct vmcb *vmcb = svm->vmcb;
+
+ if (!avic)
+ return;
+
+ vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
}

static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
@@ -4318,6 +4543,9 @@ static struct kvm_x86_ops svm_x86_ops = {
.vcpu_free = svm_free_vcpu,
.vcpu_reset = svm_vcpu_reset,

+ .vm_init = avic_vm_init,
+ .vm_uninit = avic_vm_uninit,
+
.prepare_guest_switch = svm_prepare_guest_switch,
.vcpu_load = svm_vcpu_load,
.vcpu_put = svm_vcpu_put,
@@ -4375,6 +4603,8 @@ static struct kvm_x86_ops svm_x86_ops = {
.refresh_apicv_exec_ctrl = svm_refresh_apicv_exec_ctrl,
.load_eoi_exitmap = svm_load_eoi_exitmap,
.sync_pir_to_irr = svm_sync_pir_to_irr,
+ .hwapic_irr_update = svm_hwapic_irr_update,
+ .hwapic_isr_update = svm_hwapic_isr_update,

.set_tss_addr = svm_set_tss_addr,
.get_tdp_level = get_npt_level,
--
1.9.1