[PATCH v4 3/6] target/i386: Adjust maximum number of PMU counters

[Zide Chen <zide.chen@intel.com>]

Changing either MAX_GP_COUNTERS or MAX_FIXED_COUNTERS affects the
VMState layout and therefore requires bumping the migration version
IDs.  Adjust both limits together to avoid repeated VMState version
bumps in follow-up patches.

To support full-width writes, QEMU needs to handle the alias MSRs
starting at 0x4c1.  With the current limits, the alias range can
extend into MSR_MCG_EXT_CTL (0x4d0).  Reducing MAX_GP_COUNTERS from 18
to 15 avoids the overlap while still leaving room for future expansion
beyond current hardware (which supports at most 10 GP counters).

Increase MAX_FIXED_COUNTERS to 7 to support additional fixed counters
(e.g. Topdown metric events).

With these changes, bump version_id to prevent migration to older
QEMU, and bump minimum_version_id to prevent migration from older
QEMU, which could otherwise result in VMState overflows.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
 target/i386/cpu.h     | 8 ++------
 target/i386/machine.c | 4 ++--
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index ff44487d0b6d..5288c92fe52f 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1751,12 +1751,8 @@ typedef struct {
 #define CPU_NB_REGS CPU_NB_REGS32
 #endif
 
-#define MAX_FIXED_COUNTERS 3
-/*
- * This formula is based on Intel's MSR. The current size also meets AMD's
- * needs.
- */
-#define MAX_GP_COUNTERS    (MSR_IA32_PERF_STATUS - MSR_P6_EVNTSEL0)
+#define MAX_FIXED_COUNTERS 7
+#define MAX_GP_COUNTERS    15
 
 #define NB_OPMASK_REGS 8
 
diff --git a/target/i386/machine.c b/target/i386/machine.c
index e0a5a5da6f5a..05aa38a8a43d 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -685,8 +685,8 @@ static bool pmu_enable_needed(void *opaque)
 
 static const VMStateDescription vmstate_msr_architectural_pmu = {
     .name = "cpu/msr_architectural_pmu",
-    .version_id = 1,
-    .minimum_version_id = 1,
+    .version_id = 2,
+    .minimum_version_id = 2,
     .needed = pmu_enable_needed,
     .fields = (const VMStateField[]) {
         VMSTATE_UINT64(env.msr_fixed_ctr_ctrl, X86CPU),
-- 
2.54.0