[Xen-devel] [PATCH RFC v1 49/74] x86/guest: map per-cpu vcpu_info area.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

So that the limit of XEN_LEGACY_MAX_VCPUS can be lifted.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Should be moved earlier maybe?
---
 xen/arch/x86/guest/xen.c              | 61 +++++++++++++++++++++++++++++++++--
 xen/arch/x86/time.c                   | 11 ++-----
 xen/include/asm-x86/guest/hypercall.h |  7 ++++
 3 files changed, 69 insertions(+), 10 deletions(-)

diff --git a/xen/arch/x86/guest/xen.c b/xen/arch/x86/guest/xen.c
index a95c36017f..3fa164aba8 100644
--- a/xen/arch/x86/guest/xen.c
+++ b/xen/arch/x86/guest/xen.c
@@ -38,6 +38,10 @@ static struct rangeset *mem;
 
 DEFINE_PER_CPU(unsigned int, vcpu_id);
 
+static struct vcpu_info *vcpu_info;
+unsigned long vcpu_info_mapped[BITS_TO_LONGS(NR_CPUS)];
+DEFINE_PER_CPU(struct vcpu_info *, vcpu_info);
+
 static void __init find_xen_leaves(void)
 {
     uint32_t eax, ebx, ecx, edx, base;
@@ -101,6 +105,38 @@ static void map_shared_info(void)
         xchg(&XEN_shared_info->evtchn_mask[i], ~0ul);
 }
 
+static int map_vcpuinfo(void)
+{
+    unsigned int vcpu = this_cpu(vcpu_id);
+    struct vcpu_register_vcpu_info info = { };
+    long rc;
+
+    if ( !vcpu_info )
+    {
+        this_cpu(vcpu_info) = &XEN_shared_info->vcpu_info[vcpu];
+        return 0;
+    }
+
+    if ( test_bit(vcpu, vcpu_info_mapped) )
+    {
+        this_cpu(vcpu_info) = &vcpu_info[vcpu];
+        return 0;
+    }
+
+    info.mfn = virt_to_mfn(&vcpu_info[vcpu]);
+    info.offset = (unsigned long)&vcpu_info[vcpu] & ~PAGE_MASK;
+    rc = xen_hypercall_vcpu_op(VCPUOP_register_vcpu_info, vcpu, &info);
+    if ( rc )
+        this_cpu(vcpu_info) = &XEN_shared_info->vcpu_info[vcpu];
+    else
+    {
+        this_cpu(vcpu_info) = &vcpu_info[vcpu];
+        set_bit(vcpu, vcpu_info_mapped);
+    }
+
+    return rc;
+}
+
 static void set_vcpu_id(void)
 {
     uint32_t eax, ebx, ecx, edx;
@@ -117,8 +153,7 @@ static void set_vcpu_id(void)
 
 static void xen_evtchn_upcall(struct cpu_user_regs *regs)
 {
-    struct vcpu_info *vcpu_info =
-        &XEN_shared_info->vcpu_info[this_cpu(vcpu_id)];
+    struct vcpu_info *vcpu_info = this_cpu(vcpu_info);
 
     vcpu_info->evtchn_upcall_pending = 0;
     xchg(&vcpu_info->evtchn_pending_sel, 0);
@@ -176,12 +211,34 @@ void __init hypervisor_setup(void)
     map_shared_info();
     set_vcpu_id();
 
+    vcpu_info = xzalloc_array(struct vcpu_info, nr_cpu_ids);
+    if ( map_vcpuinfo() || !vcpu_info )
+    {
+        if ( vcpu_info )
+        {
+            xfree(vcpu_info);
+            vcpu_info = NULL;
+        }
+        if ( nr_cpu_ids > XEN_LEGACY_MAX_VCPUS )
+        {
+            unsigned int i;
+
+            for ( i = XEN_LEGACY_MAX_VCPUS; i < nr_cpu_ids; i++ )
+                __cpumask_clear_cpu(i, &cpu_present_map);
+            nr_cpu_ids = XEN_LEGACY_MAX_VCPUS;
+            printk(XENLOG_WARNING
+                   "unable to map vCPU info, limiting vCPUs to: %u\n",
+                   XEN_LEGACY_MAX_VCPUS);
+        }
+    }
+
     init_evtchn();
 }
 
 void hypervisor_ap_setup(void)
 {
     set_vcpu_id();
+    map_vcpuinfo();
     init_evtchn();
 }
 
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 85bcb9b28a..1294c88240 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -533,11 +533,11 @@ static struct platform_timesource __initdata plt_tsc =
  * Xen clock source is a variant of TSC source.
  */
 
-DECLARE_PER_CPU(unsigned int, vcpu_id);
+DECLARE_PER_CPU(struct vcpu_info *, vcpu_info);
 
 static u64 xen_timer_cpu_frequency(void)
 {
-    struct vcpu_time_info *info = &XEN_shared_info->vcpu_info[0].time;
+    struct vcpu_time_info *info = &this_cpu(vcpu_info)->time;
     u64 freq;
 
     freq = 1000000000ULL << 32;
@@ -576,16 +576,11 @@ u64 __read_cycle(const struct vcpu_time_info *info, u64 
tsc)
 static u64 last_value;
 static u64 read_xen_timer(void)
 {
-    struct vcpu_time_info *info;
-    unsigned int cpu = this_cpu(vcpu_id);
+    struct vcpu_time_info *info = &this_cpu(vcpu_info)->time;
     u32 version;
     u64 ret;
     u64 last;
 
-    /* TODO: lift this restriction */
-    ASSERT(cpu < XEN_LEGACY_MAX_VCPUS);
-    info = &XEN_shared_info->vcpu_info[cpu].time;
-
     do {
         version = info->version & ~1;
         /* Make sure version is read before the data */
diff --git a/xen/include/asm-x86/guest/hypercall.h 
b/xen/include/asm-x86/guest/hypercall.h
index 90b4755467..7d11df29fa 100644
--- a/xen/include/asm-x86/guest/hypercall.h
+++ b/xen/include/asm-x86/guest/hypercall.h
@@ -23,6 +23,7 @@
 
 #include <public/xen.h>
 #include <public/sched.h>
+#include <public/vcpu.h>
 #include <public/hvm/hvm_op.h>
 
 #ifdef CONFIG_XEN_GUEST
@@ -107,6 +108,12 @@ static inline long xen_hypercall_hvm_op(unsigned int op, 
void *arg)
     return _hypercall64_2(long, __HYPERVISOR_hvm_op, op, arg);
 }
 
+static inline long xen_hypercall_vcpu_op(unsigned int cmd, unsigned int vcpu,
+                                         void *arg)
+{
+    return _hypercall64_3(long, __HYPERVISOR_vcpu_op, cmd, vcpu, arg);
+}
+
 /*
  * Higher level hypercall helpers
  */
-- 
2.11.0


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