linux/include
Sean Christopherson 700f8d2443 Revert "KVM: Check for duplicate vcpu_id as early as possible"
Now that KVM uses kvm_get_vcpu_by_id() to check for an existing vCPU ID
before doing any meaningful work, which was made possible by holding
kvm->lock for the entirety of vCPU creation, revert the now-redundant
"early" vCPU ID tracking.  The claims about the impact of kvm->vcpu_ids on
the memory footprint were a wee bit wrong: the worst case scenario isn't
256 bytes per VM, it's 256 "unsigned longs" per VM, i.e. 2048 bytes per VM.

Increasing the size of "struct kvm" by 2048 nearly doubled the total size
on many architectures, and tripped x86's KVM_SANITY_CHECK_VM_STRUCT_SIZE,
which was added to detect this *exact* scenario, where a single change
significantly increased the size of "struct kvm".  I.e. attempting to build
KVM with CONFIG_DEBUG_KERNEL=n fails on x86 (the build failures got missed
because all build bots apparently test only CONFIG_DEBUG_KERNEL=y kernels,
and maintainers' test flows were similarly lacking).

This reverts commit 97d65b544f.

Fixes: 97d65b544f ("KVM: Check for duplicate vcpu_id as early as possible")
Reported-by: Jean-Christophe Guillain <jean-christophe@guillain.net>
Closes: https://lore.kernel.org/all/56a4bc35ee605588b7cc36c8e45c12b5f3b506cb.camel@guillain.net
Reported-by: Paweł S <spawel523@gmail.com>
Closes: https://lore.kernel.org/all/CABD%3DWFOS4j4hDv%2BpW-eEM9HAM2q2GY_iYdAG%2BqvYcUEinUrcQQ@mail.gmail.com
Tested-by: Jean-Christophe Guillain <jean-christophe@guillain.net>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Naveen N Rao (AMD) <naveen@kernel.org>
Message-ID: <20260921174445.911676-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2026-09-26 00:49:49 -04:00
..
acpi ACPI: bus: Drop two fields from struct acpi_device_pnp 2026-09-01 21:45:50 +02:00
asm-generic kho: make boot time huge page allocation work nicely with KHO 2026-08-23 09:17:38 -07:00
clocksource hyperv-next for v7.3-rc1 2026-08-26 16:47:40 -07:00
crypto This update includes the following changes: 2026-08-19 17:25:42 -07:00
cxl
drm Merge drm/drm-fixes into drm-misc-fixes 2026-09-01 09:38:51 +02:00
dt-bindings sound fixes for 7.3-rc1 2026-08-28 10:01:02 -07:00
hyperv
keys tpm: Initial step to reorganize TPM public headers 2026-08-25 18:13:35 +03:00
kunit gpio updates for v7.3-rc1 2026-08-19 09:10:07 -07:00
kvm KVM/arm64 changes for 7.3 2026-08-24 12:42:07 -04:00
linux Revert "KVM: Check for duplicate vcpu_id as early as possible" 2026-09-26 00:49:49 -04:00
math-emu
media media: hevc: add bounded tile-count helpers 2026-09-07 09:01:05 +02:00
memory
misc
net net: ipv6: Clamp to IP6_MAX_MTU in ip6_dst_mtu_maybe_forward 2026-09-07 17:13:55 -07:00
pcmcia
ras
rdma
rv mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
scsi SCSI updates for 7.3 2026-08-29 11:55:36 -07:00
soc Mostly the usual clk driver updates and new SoC additions plus non-critical 2026-08-26 11:14:30 -07:00
sound ALSA: rawmidi: Another workaround for false-positive mutex lockdep warning 2026-08-25 15:55:37 +02:00
target
trace tracing fixes for 7.3: 2026-09-13 12:27:00 -07:00
uapi integrity-v7.3-rc2 2026-09-04 19:36:11 -07:00
ufs
vdso
video fbdev: maxine: fix 64-bit build error 2026-08-20 23:45:07 +02:00
xen
Kbuild