add helpers to read etc/boot-cpus at resume time

Signed-off-by: Igor Mammedov <imammedo@redhat.com>

3 files changed, 47 insertions, 5 deletions

diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c
index 33a471b..125066d 100644
--- a/src/fw/paravirt.c
+++ b/src/fw/paravirt.c
@@ -319,6 +319,44 @@ qemu_romfile_add(char *name, int select, int skip, int size)
     romfile_add(&qfile->file);
 }
 
+static int
+qemu_romfile_get_fwcfg_entry(char *name, int *select)
+{
+    struct romfile_s *file = romfile_find(name);
+    if (!file)
+        return 0;
+    struct qemu_romfile_s *qfile;
+    qfile = container_of(file, struct qemu_romfile_s, file);
+    if (select)
+        *select = qfile->select;
+    return file->size;
+}
+
+static int boot_cpus_sel;
+static int boot_cpus_file_sz;
+
+u16
+qemu_init_present_cpus_count(void)
+{
+    u16 smp_count = romfile_loadint("etc/boot-cpus",
+                                    rtc_read(CMOS_BIOS_SMP_COUNT) + 1);
+    boot_cpus_file_sz =
+        qemu_romfile_get_fwcfg_entry("etc/boot-cpus", &boot_cpus_sel);
+    return smp_count;
+}
+
+u16
+qemu_get_present_cpus_count(void)
+{
+    u16 smp_count;
+    if (!boot_cpus_file_sz) {
+        smp_count = rtc_read(CMOS_BIOS_SMP_COUNT) + 1;
+    } else {
+        qemu_cfg_read_entry(&smp_count, boot_cpus_sel, boot_cpus_file_sz);
+    }
+    return smp_count;
+}
+
 struct e820_reservation {
     u64 address;
     u64 length;
diff --git a/src/fw/paravirt.h b/src/fw/paravirt.h
index ed8e5f1..6f26fd0 100644
--- a/src/fw/paravirt.h
+++ b/src/fw/paravirt.h
@@ -52,4 +52,7 @@ void qemu_preinit(void);
 void qemu_platform_setup(void);
 void qemu_cfg_init(void);
 
+u16 qemu_init_present_cpus_count(void);
+u16 qemu_get_present_cpus_count(void);
+
 #endif
diff --git a/src/fw/smp.c b/src/fw/smp.c
index 31bcc6a..9c404b9 100644
--- a/src/fw/smp.c
+++ b/src/fw/smp.c
@@ -12,6 +12,7 @@
 #include "stacks.h" // yield
 #include "util.h" // smp_setup, msr_feature_control_setup
 #include "x86.h" // wrmsr
+#include "paravirt.h" // qemu_*_present_cpus_count
 
 #define APIC_ICR_LOW ((u8*)BUILD_APIC_ADDR + 0x300)
 #define APIC_SVR     ((u8*)BUILD_APIC_ADDR + 0x0F0)
@@ -131,8 +132,8 @@ smp_scan(void)
     writel(APIC_ICR_LOW, 0x000C4600 | sipi_vector);
 
     // Wait for other CPUs to process the SIPI.
-    u8 cmos_smp_count = rtc_read(CMOS_BIOS_SMP_COUNT) + 1;
-    while (cmos_smp_count != CountCPUs)
+    u16 expected_cpus_count = qemu_get_present_cpus_count();
+    while (expected_cpus_count != CountCPUs)
         asm volatile(
             // Release lock and allow other processors to use the stack.
             "  movl %%esp, %1\n"
@@ -159,9 +160,9 @@ smp_setup(void)
         return;
 
     MaxCountCPUs = romfile_loadint("etc/max-cpus", 0);
-    u8 cmos_smp_count = rtc_read(CMOS_BIOS_SMP_COUNT) + 1;
-    if (MaxCountCPUs < cmos_smp_count)
-        MaxCountCPUs = cmos_smp_count;
+    u16 smp_count = qemu_init_present_cpus_count();
+    if (MaxCountCPUs < smp_count)
+        MaxCountCPUs = smp_count;
 
     smp_scan();
 }