Re: [PATCH v4 0/5] Support x2APIC mode with TCG accelerator

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, May 22, 2023 at 11:31:52PM +0700, Bui Quang Minh wrote:
> Hi everyone,
> 
> This series implements x2APIC mode in userspace local APIC and the
> RDMSR/WRMSR helper to access x2APIC registers in x2APIC mode. Intel iommu
> and AMD iommu are adjusted to support x2APIC interrupt remapping. With this
> series, we can now boot Linux kernel into x2APIC mode with TCG accelerator
> using either Intel or AMD iommu.
> 
> Testing to boot my own built Linux 6.3.0-rc2, the kernel successfully boot
> with enabled x2APIC and can enumerate CPU with APIC ID 257
> Using Intel IOMMU
> 
> qemu/build/qemu-system-x86_64 \
>   -smp 2,maxcpus=260 \
>   -cpu qemu64,x2apic=on \
>   -machine q35 \
>   -device intel-iommu,intremap=on,eim=on \
>   -device qemu64-x86_64-cpu,x2apic=on,core-id=257,socket-id=0,thread-id=0 \
>   -m 2G \
>   -kernel $KERNEL_DIR \
>   -append "nokaslr console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0" \
>   -drive file=$IMAGE_DIR,format=raw \
>   -nographic \
>   -s
> 
> Using AMD IOMMU
> 
> qemu/build/qemu-system-x86_64 \
>   -smp 2,maxcpus=260 \
>   -cpu qemu64,x2apic=on \
>   -machine q35 \
>   -device amd-iommu,intremap=on,xtsup=on \
>   -device qemu64-x86_64-cpu,x2apic=on,core-id=257,socket-id=0,thread-id=0 \
>   -m 2G \
>   -kernel $KERNEL_DIR \
>   -append "nokaslr console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0" \
>   -drive file=$IMAGE_DIR,format=raw \
>   -nographic \
>   -s
> 
> Testing the emulated userspace APIC with kvm-unit-tests, disable test
> device with this patch
> 
> diff --git a/lib/x86/fwcfg.c b/lib/x86/fwcfg.c
> index 1734afb..f56fe1c 100644
> --- a/lib/x86/fwcfg.c
> +++ b/lib/x86/fwcfg.c
> @@ -27,6 +27,7 @@ static void read_cfg_override(void)
>  
>         if ((str = getenv("TEST_DEVICE")))
>                 no_test_device = !atol(str);
> +       no_test_device = true;
>  
>         if ((str = getenv("MEMLIMIT")))
>                 fw_override[FW_CFG_MAX_RAM] = atol(str) * 1024 * 1024;
> 
> ~ env QEMU=/home/minh/Desktop/oss/qemu/build/qemu-system-x86_64 ACCEL=tcg \
> ./run_tests.sh -v -g apic 
> 
> TESTNAME=apic-split TIMEOUT=90s ACCEL=tcg ./x86/run x86/apic.flat -smp 2
> -cpu qemu64,+x2apic,+tsc-deadline -machine kernel_irqchip=split FAIL
> apic-split (54 tests, 8 unexpected failures, 1 skipped)
> TESTNAME=ioapic-split TIMEOUT=90s ACCEL=tcg ./x86/run x86/ioapic.flat -smp
> 1 -cpu qemu64 -machine kernel_irqchip=split PASS ioapic-split (19 tests)
> TESTNAME=x2apic TIMEOUT=30 ACCEL=tcg ./x86/run x86/apic.flat -smp 2 -cpu
> qemu64,+x2apic,+tsc-deadline FAIL x2apic (54 tests, 8 unexpected failures,
> 1 skipped) TESTNAME=xapic TIMEOUT=60 ACCEL=tcg ./x86/run x86/apic.flat -smp
> 2 -cpu qemu64,-x2apic,+tsc-deadline -machine pit=off FAIL xapic (43 tests,
> 6 unexpected failures, 2 skipped)
> 
>   FAIL: apic_disable: *0xfee00030: 50014
>   FAIL: apic_disable: *0xfee00080: f0
>   FAIL: apic_disable: *0xfee00030: 50014
>   FAIL: apic_disable: *0xfee00080: f0 
>   FAIL: apicbase: relocate apic
> 
> These errors are because we don't disable MMIO region when switching to
> x2APIC and don't support relocate MMIO region yet. This is a problem
> because, MMIO region is the same for all CPUs, in order to support these we
> need to figure out how to allocate and manage different MMIO regions for
> each CPUs.

Oh interesting point.
Paolo what do you say? Can memory core support something like this?

> This can be an improvement in the future.
> 
>   FAIL: nmi-after-sti
>   FAIL: multiple nmi
> 
> These errors are in the way we handle CPU_INTERRUPT_NMI in core TCG.
> 
>   FAIL: TMCCT should stay at zero
> 
> This error is related to APIC timer which should be addressed in separate
> patch.
> 
> Version 4 changes,
> - Patch 5:
>   + Instead of replacing IVHD type 0x10 with type 0x11, export both types
>   for backward compatibility with old guest operating system
>   + Flip the xtsup feature check condition in amdvi_int_remap_ga for
>   readability
> 
> Version 3 changes,
> - Patch 2:
>   + Allow APIC ID > 255 only when x2APIC feature is supported on CPU
>   + Make physical destination mode IPI which has destination id 0xffffffff
>   a broadcast to xAPIC CPUs
>   + Make cluster address 0xf in cluster model of xAPIC logical destination
>   mode a broadcast to all clusters
>   + Create new extended_log_dest to store APIC_LDR information in x2APIC
>   instead of extending log_dest for backward compatibility in vmstate
> 
> Version 2 changes,
> - Add support for APIC ID larger than 255
> - Adjust AMD iommu for x2APIC suuport
> - Reorganize and split patch 1,2 into patch 1,2,3 in version 2
> 
> Thanks,
> Quang Minh.
> 
> Bui Quang Minh (5):
>   i386/tcg: implement x2APIC registers MSR access
>   apic: add support for x2APIC mode
>   apic, i386/tcg: add x2apic transitions
>   intel_iommu: allow Extended Interrupt Mode when using userspace APIC
>   amd_iommu: report x2APIC support to the operating system
> 
>  hw/i386/acpi-build.c                 | 127 +++++----
>  hw/i386/amd_iommu.c                  |  21 +-
>  hw/i386/amd_iommu.h                  |  16 +-
>  hw/i386/intel_iommu.c                |  11 -
>  hw/i386/x86.c                        |   8 +-
>  hw/intc/apic.c                       | 395 +++++++++++++++++++++------
>  hw/intc/apic_common.c                |  16 +-
>  hw/intc/trace-events                 |   4 +-
>  include/hw/i386/apic.h               |   6 +-
>  include/hw/i386/apic_internal.h      |   7 +-
>  target/i386/cpu-sysemu.c             |  18 +-
>  target/i386/cpu.c                    |   5 +-
>  target/i386/cpu.h                    |   9 +
>  target/i386/tcg/sysemu/misc_helper.c |  31 +++
>  14 files changed, 500 insertions(+), 174 deletions(-)
> 
> -- 
> 2.25.1