[SeaBIOS] [PATCH] fw/mptable: fix smp core initialization per cpu package

[Anthony Iliopoulos]

Currently the mptable setup code only considers one core per cpu package
for populating the cpu tables. The detection logic goes back to machines
where the cpuid would signify the presence of multiple logical cores
(HT) and presumably this change was made to prevent creating vcpus for
each hyperthread.

In practice this restriction is not required any longer especially since
current processors feature many physical cores per socket, and it is
preventing QEMU guests that don't enable ACPI from seeing more than one
cores, unless those cores are explicitly placed across multiple sockets
(one core per socket, specifically).

During v6.2 QEMU changed the default cpu topology arrangement preference
from arranging multiple cores spreaded across multiple sockets to
placing them within the same socket [1]. In practice this means that
without specifing explicitly the cpu topology and assuming QEMU
defaults, a guest without ACPI will not be able to instantiate more than
one core.

Fix this by lifting the restriction of only populating the mptable with
the first logical processor per package.

[1] commit 4a0af2930a4e ("machine: Prefer cores over sockets in smp
parsing since 6.2")

Fixes: c0ad0e8febe5 ("Only add the first logical CPU in each physical
CPU to the MPS tables.")

Signed-off-by: Anthony Iliopoulos 
---
 src/fw/mptable.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/src/fw/mptable.c b/src/fw/mptable.c
index 47385cc5d32d..a939743691c9 100644
--- a/src/fw/mptable.c
+++ b/src/fw/mptable.c
@@ -47,19 +47,13 @@ mptable_setup(void)
         cpuid_signature = 0x600;
         cpuid_features = 0x201;
     }
-    int pkgcpus = 1;
-    if (cpuid_features & (1 << 28)) {
-        /* Only populate the MPS tables with the first logical CPU in
-           each package */
-        pkgcpus = (ebx >> 16) & 0xff;
-        pkgcpus = 1 << (__fls(pkgcpus - 1) + 1); /* round up to power of 2 */
-    }
+
     u8 apic_version = readl((u8*)BUILD_APIC_ADDR + 0x30) & 0xff;

// CPU definitions.
     struct mpt_cpu *cpus = (void*)&config[1], *cpu = cpus;
     int i;
-    for (i = 0; i < MaxCountCPUs; i+=pkgcpus) {
+    for (i = 0; i < MaxCountCPUs; i++) {
         memset(cpu, 0, sizeof(*cpu));
         cpu->type = MPT_TYPE_CPU;
         cpu->apicid = i;