[Xen-devel] [PATCH RFC v1 46/74] xen/guest: fetch vCPU ID from Xen

[Wei Liu <wei.liu2@xxxxxxxxxx>]

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

If available.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
To be moved before "x86/guest: enable event channels upcalls"
---
 xen/arch/x86/guest/xen.c | 24 +++++++++++++++++++++---
 xen/arch/x86/time.c      |  4 +++-
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/guest/xen.c b/xen/arch/x86/guest/xen.c
index 0a4c02a8cd..0f2c5d7413 100644
--- a/xen/arch/x86/guest/xen.c
+++ b/xen/arch/x86/guest/xen.c
@@ -37,6 +37,8 @@ static uint8_t evtchn_upcall_vector;
 extern char hypercall_page[];
 static struct rangeset *mem;
 
+DEFINE_PER_CPU(unsigned int, vcpu_id);
+
 static void __init find_xen_leaves(void)
 {
     uint32_t eax, ebx, ecx, edx, base;
@@ -95,10 +97,24 @@ static void map_shared_info(void)
     set_fixmap(FIX_XEN_SHARED_INFO, mfn_x(mfn) << PAGE_SHIFT);
 }
 
+static void set_vcpu_id(void)
+{
+    uint32_t eax, ebx, ecx, edx;
+
+    ASSERT(xen_cpuid_base);
+
+    /* Fetch vcpu id from cpuid. */
+    cpuid(xen_cpuid_base + 4, &eax, &ebx, &ecx, &edx);
+    if ( eax & XEN_HVM_CPUID_VCPU_ID_PRESENT )
+        this_cpu(vcpu_id) = ebx;
+    else
+        this_cpu(vcpu_id) = smp_processor_id();
+}
+
 static void xen_evtchn_upcall(struct cpu_user_regs *regs)
 {
-    unsigned int cpu = smp_processor_id();
-    struct vcpu_info *vcpu_info = &XEN_shared_info->vcpu_info[cpu];
+    struct vcpu_info *vcpu_info =
+        &XEN_shared_info->vcpu_info[this_cpu(vcpu_id)];
 
     vcpu_info->evtchn_upcall_pending = 0;
     xchg(&vcpu_info->evtchn_pending_sel, 0);
@@ -110,7 +126,7 @@ static void xen_evtchn_upcall(struct cpu_user_regs *regs)
 
 static void ap_setup_event_channels(bool clear)
 {
-    unsigned int i, cpu = smp_processor_id();
+    unsigned int i, cpu = this_cpu(vcpu_id);
     struct vcpu_info *vcpu_info = &XEN_shared_info->vcpu_info[cpu];
     int rc;
 
@@ -191,12 +207,14 @@ void __init hypervisor_setup(void)
     init_memmap();
 
     map_shared_info();
+    set_vcpu_id();
 
     init_evtchn();
 }
 
 void hypervisor_ap_setup(void)
 {
+    set_vcpu_id();
     ap_setup_event_channels(false);
 }
 
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 886fc45248..85bcb9b28a 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -533,6 +533,8 @@ static struct platform_timesource __initdata plt_tsc =
  * Xen clock source is a variant of TSC source.
  */
 
+DECLARE_PER_CPU(unsigned int, vcpu_id);
+
 static u64 xen_timer_cpu_frequency(void)
 {
     struct vcpu_time_info *info = &XEN_shared_info->vcpu_info[0].time;
@@ -575,7 +577,7 @@ static u64 last_value;
 static u64 read_xen_timer(void)
 {
     struct vcpu_time_info *info;
-    unsigned int cpu = smp_processor_id();
+    unsigned int cpu = this_cpu(vcpu_id);
     u32 version;
     u64 ret;
     u64 last;
-- 
2.11.0


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