[PATCH 01/11] Add shared memory hypercall to PV Linux guest.

From: Gleb Natapov
Date: Sun Nov 01 2009 - 06:56:47 EST

Add hypercall that allows guest and host to setup per cpu shared
memory.

Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 3 +
arch/x86/include/asm/kvm_para.h | 11 +++++
arch/x86/kernel/kvm.c | 82 +++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/setup.c | 1 +
arch/x86/kernel/smpboot.c | 3 +
arch/x86/kvm/x86.c | 70 +++++++++++++++++++++++++++++++++
include/linux/kvm.h | 1 +
include/linux/kvm_para.h | 4 ++
8 files changed, 175 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 26a74b7..2d1f526 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -374,6 +374,9 @@ struct kvm_vcpu_arch {
/* used for guest single stepping over the given code position */
u16 singlestep_cs;
unsigned long singlestep_rip;
+
+ struct kvm_vcpu_pv_shm *pv_shm;
+ struct page *pv_shm_page;
};

struct kvm_mem_alias {
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index c584076..90708b7 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -15,6 +15,7 @@
#define KVM_FEATURE_CLOCKSOURCE 0
#define KVM_FEATURE_NOP_IO_DELAY 1
#define KVM_FEATURE_MMU_OP 2
+#define KVM_FEATURE_ASYNC_PF 3

#define MSR_KVM_WALL_CLOCK 0x11
#define MSR_KVM_SYSTEM_TIME 0x12
@@ -47,6 +48,16 @@ struct kvm_mmu_op_release_pt {
__u64 pt_phys;
};

+#define KVM_PV_SHM_VERSION 1
+
+#define KVM_PV_SHM_FEATURES_ASYNC_PF (1 << 0)
+
+struct kvm_vcpu_pv_shm {
+ __u64 features;
+ __u64 reason;
+ __u64 param;
+};
+
#ifdef __KERNEL__
#include <asm/processor.h>

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 63b0ec8..d03f33c 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -27,7 +27,11 @@
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/hardirq.h>
+#include <linux/bootmem.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
#include <asm/timer.h>
+#include <asm/cpu.h>

#define MMU_QUEUE_SIZE 1024

@@ -37,6 +41,7 @@ struct kvm_para_state {
};

static DEFINE_PER_CPU(struct kvm_para_state, para_state);
+static DEFINE_PER_CPU(struct kvm_vcpu_pv_shm *, kvm_vcpu_pv_shm);

static struct kvm_para_state *kvm_para_state(void)
{
@@ -50,6 +55,17 @@ static void kvm_io_delay(void)
{
}

+static void kvm_end_context_switch(struct task_struct *next)
+{
+ struct kvm_vcpu_pv_shm *pv_shm =
+ per_cpu(kvm_vcpu_pv_shm, smp_processor_id());
+
+ if (!pv_shm)
+ return;
+
+ pv_shm->current_task = (u64)next;
+}
+
static void kvm_mmu_op(void *buffer, unsigned len)
{
int r;
@@ -231,10 +247,76 @@ static void __init paravirt_ops_setup(void)
#endif
}

+static void kvm_pv_unregister_shm(void *unused)
+{
+ if (per_cpu(kvm_vcpu_pv_shm, smp_processor_id()) == NULL)
+ return;
+
+ kvm_hypercall3(KVM_HC_SETUP_SHM, 0, 0, KVM_PV_SHM_VERSION);
+ printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
+ smp_processor_id());
+
+}
+
+static int kvm_pv_reboot_notify(struct notifier_block *nb,
+ unsigned long code, void *unused)
+{
+ if (code == SYS_RESTART)
+ on_each_cpu(kvm_pv_unregister_shm, NULL, 1);
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_pv_reboot_nb = {
+ .notifier_call = kvm_pv_reboot_notify,
+};
+
void __init kvm_guest_init(void)
{
if (!kvm_para_available())
return;

paravirt_ops_setup();
+ register_reboot_notifier(&kvm_pv_reboot_nb);
+}
+
+void __cpuinit kvm_guest_cpu_init(void)
+{
+ int r;
+ unsigned long a0, a1, a2;
+ struct kvm_vcpu_pv_shm *pv_shm;
+
+ if (!kvm_para_available())
+ return;
+
+ if (smp_processor_id() == boot_cpu_id)
+ pv_shm = alloc_bootmem(sizeof(*pv_shm));
+ else
+ pv_shm = kmalloc(sizeof(*pv_shm), GFP_ATOMIC);
+
+ if (!pv_shm)
+ return;
+
+ memset(pv_shm, 0, sizeof(*pv_shm));
+
+ if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
+ pv_shm->features |= KVM_PV_SHM_FEATURES_ASYNC_PF;
+
+ per_cpu(kvm_vcpu_pv_shm, smp_processor_id()) = pv_shm;
+ a0 = __pa(pv_shm);
+ a1 = sizeof(*pv_shm);
+ a2 = KVM_PV_SHM_VERSION;
+ r = kvm_hypercall3(KVM_HC_SETUP_SHM, a0, a1, a2);
+
+ if (!r) {
+ printk(KERN_INFO"Setup pv shared memory for cpu %d\n",
+ smp_processor_id());
+ return;
+ }
+
+ if (smp_processor_id() == boot_cpu_id)
+ free_bootmem(__pa(pv_shm), sizeof(*pv_shm));
+ else
+ kfree(pv_shm);
+
+ per_cpu(kvm_vcpu_pv_shm, smp_processor_id()) = NULL;
}
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index e09f0e2..1c2f8dd 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1007,6 +1007,7 @@ void __init setup_arch(char **cmdline_p)
probe_nr_irqs_gsi();

kvm_guest_init();
+ kvm_guest_cpu_init();

e820_reserve_resources();
e820_mark_nosave_regions(max_low_pfn);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 565ebc6..5599098 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -65,6 +65,7 @@
#include <asm/setup.h>
#include <asm/uv/uv.h>
#include <linux/mc146818rtc.h>
+#include <linux/kvm_para.h>

#include <asm/smpboot_hooks.h>

@@ -321,6 +322,8 @@ notrace static void __cpuinit start_secondary(void *unused)
ipi_call_unlock();
per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;

+ kvm_guest_cpu_init();
+
/* enable local interrupts */
local_irq_enable();

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2ef3906..c177933 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1342,6 +1342,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_SET_IDENTITY_MAP_ADDR:
case KVM_CAP_XEN_HVM:
case KVM_CAP_ADJUST_CLOCK:
+ case KVM_CAP_ASYNC_PF:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -3371,6 +3372,68 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_emulate_halt);

+static void kvm_pv_release_shm(struct kvm_vcpu *vcpu)
+{
+ if (!vcpu->arch.pv_shm_page)
+ return;
+
+ kunmap(vcpu->arch.pv_shm_page);
+ put_page(vcpu->arch.pv_shm_page);
+ vcpu->arch.pv_shm_page = NULL;
+ vcpu->arch.pv_shm = NULL;
+}
+
+static int kvm_pv_setup_shm(struct kvm_vcpu *vcpu, unsigned long gpa,
+ unsigned long size, unsigned long version,
+ unsigned long *ret)
+{
+ int r;
+ unsigned long addr;
+ gfn_t gfn = gpa >> PAGE_SHIFT;
+ int offset = offset_in_page(gpa);
+ struct mm_struct *mm = current->mm;
+ void *p;
+
+ *ret = -KVM_EINVAL;
+
+ if (size == 0 && vcpu->arch.pv_shm != NULL &&
+ version == KVM_PV_SHM_VERSION) {
+ kvm_pv_release_shm(vcpu);
+ goto out;
+ }
+
+ if (vcpu->arch.pv_shm != NULL || size != sizeof(*vcpu->arch.pv_shm) ||
+ size > PAGE_SIZE || version != KVM_PV_SHM_VERSION)
+ return -EINVAL;
+
+ *ret = -KVM_EFAULT;
+
+ addr = gfn_to_hva(vcpu->kvm, gfn);
+ if (kvm_is_error_hva(addr))
+ return -EFAULT;
+
+ /* pin page with pv shared memory */
+ down_read(&mm->mmap_sem);
+ r = get_user_pages(current, mm, addr, 1, 1, 0, &vcpu->arch.pv_shm_page,
+ NULL);
+ up_read(&mm->mmap_sem);
+ if (r != 1)
+ return -EFAULT;
+
+ p = kmap(vcpu->arch.pv_shm_page);
+ if (!p) {
+ put_page(vcpu->arch.pv_shm_page);
+ vcpu->arch.pv_shm_page = NULL;
+ return -ENOMEM;
+ }
+
+ vcpu->arch.pv_shm = p + offset;
+
+out:
+ *ret = 0;
+ return 0;
+}
+
static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
unsigned long a1)
{
@@ -3413,6 +3476,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
case KVM_HC_MMU_OP:
r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
break;
+ case KVM_HC_SETUP_SHM:
+ r = kvm_pv_setup_shm(vcpu, a0, a1, a2, &ret);
+ break;
default:
ret = -KVM_ENOSYS;
break;
@@ -4860,6 +4926,8 @@ free_vcpu:

void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
+ kvm_pv_release_shm(vcpu);
+
vcpu_load(vcpu);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
@@ -4877,6 +4945,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
vcpu->arch.dr6 = DR6_FIXED_1;
vcpu->arch.dr7 = DR7_FIXED_1;

+ kvm_pv_release_shm(vcpu);
+
return kvm_x86_ops->vcpu_reset(vcpu);
}

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 6ed1a12..2fec4a2 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -440,6 +440,7 @@ struct kvm_ioeventfd {
#define KVM_CAP_XEN_HVM 38
#endif
#define KVM_CAP_ADJUST_CLOCK 39
+#define KVM_CAP_ASYNC_PF 40

#ifdef KVM_CAP_IRQ_ROUTING

diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index d731092..1c37495 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -14,9 +14,11 @@
#define KVM_EFAULT EFAULT
#define KVM_E2BIG E2BIG
#define KVM_EPERM EPERM
+#define KVM_EINVAL EINVAL

#define KVM_HC_VAPIC_POLL_IRQ 1
#define KVM_HC_MMU_OP 2
+#define KVM_HC_SETUP_SHM 3

/*
* hypercalls use architecture specific
@@ -26,8 +28,10 @@
#ifdef __KERNEL__
#ifdef CONFIG_KVM_GUEST
void __init kvm_guest_init(void);
+void __cpuinit kvm_guest_cpu_init(void);
#else
#define kvm_guest_init() do { } while (0)
+#define kvm_guest_cpu_init() do { } while (0)
#endif

static inline int kvm_para_has_feature(unsigned int feature)
--
1.6.3.3

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