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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH 5/6] xen/arm: exclude xen,reg{-cacheable} from domU extended regions
On Sun, 4 May 2025, Stewart Hildebrand wrote:
> When a device is passed through to a dom0less domU, the
> xen,reg{-cacheable} ranges may overlap with the extended regions. Remove
> xen,reg{-cacheable} from extended regions.
There is no reg-cacheable upstream, the commit message should avoid
mentioning it
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
> ---
> Not sure if we need a Fixes: tag, but if we do:
> Fixes: 2a2447757b3c ("xen/arm: implement domU extended regions")
>
> I investigated an alternate approach of parsing the partial device tree
> again to scan for xen,reg{-cacheable} properties, but it resulted in
> quite a lot of code duplication. Adding a rangeset pointer to "struct
> kernel_info" has a much smaller diffstat, and then we avoid the need to
> parse the partial device tree a second time.
>
> I discovered this issue when booting a dom0less domU with a device
> passed through. Partial device tree excerpt:
>
> passthrough {
> ... <snip> ...
>
> axi_uart16550_0: serial@a0001000 {
> clocks = <&uart_fixed_clk>;
> compatible = "ns16550a";
> interrupt-parent = <&gic>;
> interrupts = <0 89 4>;
> reg = <0x0 0xa0001000 0x0 0x1000>;
> reg-shift = <2>;
>
> xen,reg = <0x0 0xa0001000 0x00 0x1000 0x0 0xa0001000>;
> xen,path = "/amba_pl@0/serial@a0000000";
> xen,force-assign-without-iommu;
> };
> };
>
> The domU was assigned an extended region overlapping with MMIO of the
> passed through device:
>
> (XEN) d1: extended region 0: 0xa0000000->0x100000000
> (XEN) d1: extended region 1: 0x200000000->0xf000000000
>
> The domU panicked when attempting to initialize the device:
>
> [ 3.490068] a0001000.serial: ttyS0 at MMIO 0xa0001000 (irq = 15, base_baud
> = 6249375) is a 16550A
> [ 3.498843] Unable to handle kernel NULL pointer dereference at virtual
> address 0000000000000010
> [ 3.498853] Mem abort info:
> [ 3.498855] ESR = 0x0000000096000044
> [ 3.498859] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 3.498864] SET = 0, FnV = 0
> [ 3.498867] EA = 0, S1PTW = 0
> [ 3.498870] FSC = 0x04: level 0 translation fault
> [ 3.498874] Data abort info:
> [ 3.498876] ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000
> [ 3.498879] CM = 0, WnR = 1, TnD = 0, TagAccess = 0
> [ 3.498884] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
> [ 3.498888] [0000000000000010] user address but active_mm is swapper
> [ 3.498894] Internal error: Oops: 0000000096000044 [#1] SMP
> [ 3.498899] Modules linked in:
> [ 3.498908] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.10-stew
> #1
> [ 3.498917] pstate: 400000c5 (nZcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 3.498924] pc : mem_serial_out+0x18/0x20
> [ 3.498936] lr : serial8250_do_set_mctrl+0x6c/0xc0
> [ 3.498943] sp : ffff800081bab6d0
> [ 3.498946] x29: ffff800081bab6d0 x28: ffff8000815e0dc8 x27:
> ffff000001c29c60
> [ 3.498957] x26: 0000000000000000 x25: ffff00000347b900 x24:
> ffff000005504c00
> [ 3.498968] x23: ffff00000347b800 x22: 0000000000000000 x21:
> ffff800081b69d78
> [ 3.498978] x20: ffff800081b69d78 x19: 0000000000000000 x18:
> ffffffffffffffff
> [ 3.498989] x17: 3d20647561625f65 x16: 736162202c353120 x15:
> 3d20717269282030
> [ 3.498999] x14: 3030313030306178 x13: ffff800081a21ff0 x12:
> 00000000000007fe
> [ 3.499010] x11: 00000000000002aa x10: ffff800081a4dff0 x9 :
> ffff800081a21ff0
> [ 3.499020] x8 : 00000000fffff7ff x7 : ffff800081a4dff0 x6 :
> 0000000000000008
> [ 3.499030] x5 : 0000000000000000 x4 : ffff800080797584 x3 :
> 0000000000000002
> [ 3.499040] x2 : 0000000000000000 x1 : 0000000000000010 x0 :
> 0000000000000000
> [ 3.499050] Call trace:
> [ 3.499053] mem_serial_out+0x18/0x20
> [ 3.499059] serial8250_set_mctrl+0x34/0x40
> [ 3.499065] serial_core_register_port+0x534/0x7dc
> [ 3.499075] serial_ctrl_register_port+0x10/0x1c
> [ 3.499084] uart_add_one_port+0x10/0x1c
> [ 3.499092] serial8250_register_8250_port+0x308/0x4c0
> [ 3.499102] of_platform_serial_probe+0x2c4/0x48c
> [ 3.499110] platform_probe+0x68/0xdc
> [ 3.499120] really_probe+0xbc/0x298
> [ 3.499128] __driver_probe_device+0x78/0x12c
> [ 3.499135] driver_probe_device+0xdc/0x160
> [ 3.499142] __driver_attach+0x94/0x19c
> [ 3.499149] bus_for_each_dev+0x74/0xd0
> [ 3.499155] driver_attach+0x24/0x30
> [ 3.499162] bus_add_driver+0xe4/0x208
> [ 3.499168] driver_register+0x60/0x128
> [ 3.499176] __platform_driver_register+0x24/0x30
> [ 3.499184] of_platform_serial_driver_init+0x1c/0x28
> [ 3.499192] do_one_initcall+0x6c/0x1b0
> [ 3.499199] kernel_init_freeable+0x178/0x258
> [ 3.499209] kernel_init+0x20/0x1d0
> [ 3.499218] ret_from_fork+0x10/0x20
> [ 3.499228] Code: f9400800 1ac32021 8b21c001 d50332bf (39000022)
> [ 3.499233] ---[ end trace 0000000000000000 ]---
> [ 3.499237] note: swapper/0[1] exited with irqs disabled
> [ 3.499247] Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x0000000b
> [ 3.499251] SMP: stopping secondary CPUs
> [ 3.499284] Kernel Offset: disabled
> [ 3.499286] CPU features: 0x00,00000080,00200000,0200420b
> [ 3.499292] Memory Limit: none
> [ 3.792412] ---[ end Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x0000000b ]---
> ---
> xen/arch/arm/dom0less-build.c | 19 ++++++++++++++++++-
> xen/arch/arm/domain_build.c | 13 ++++++++++++-
> xen/arch/arm/include/asm/kernel.h | 1 +
> 3 files changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
> index a356fc94fc4d..23178a801818 100644
> --- a/xen/arch/arm/dom0less-build.c
> +++ b/xen/arch/arm/dom0less-build.c
> @@ -274,6 +274,14 @@ static int __init handle_passthrough_prop(struct
> kernel_info *kinfo,
> int res;
> paddr_t mstart, size, gstart;
>
> + if ( !kinfo->xen_reg_assigned )
> + {
> + kinfo->xen_reg_assigned = rangeset_new(NULL, NULL, 0);
> +
> + if ( !kinfo->xen_reg_assigned )
> + return -ENOMEM;
> + }
> +
> /* xen,reg specifies where to map the MMIO region */
> cell = (const __be32 *)xen_reg->data;
> len = fdt32_to_cpu(xen_reg->len) / ((address_cells * 2 + size_cells) *
> @@ -315,6 +323,11 @@ static int __init handle_passthrough_prop(struct
> kernel_info *kinfo,
> mstart, gstart);
> return -EFAULT;
> }
> +
> + res = rangeset_add_range(kinfo->xen_reg_assigned, PFN_DOWN(gstart),
> + PFN_DOWN(gstart + size - 1));
> + if ( res )
> + return res;
> }
>
> /*
> @@ -1006,7 +1019,11 @@ static int __init construct_domU(struct domain *d,
>
> domain_vcpu_affinity(d, node);
>
> - return alloc_xenstore_params(&kinfo);
> + rc = alloc_xenstore_params(&kinfo);
> +
> + rangeset_destroy(kinfo.xen_reg_assigned);
> +
> + return rc;
> }
>
> void __init create_domUs(void)
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 3dcdd7a8c46f..da7c7c000f1f 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -1296,6 +1296,13 @@ static int __init find_domU_holes(const struct
> kernel_info *kinfo,
> if ( res )
> goto out;
>
> + if ( kinfo->xen_reg_assigned )
> + {
> + res = rangeset_subtract(mem_holes, kinfo->xen_reg_assigned);
> + if ( res )
> + goto out;
> + }
> +
> res = rangeset_report_ranges(mem_holes, 0,
> PFN_DOWN((1ULL << p2m_ipa_bits) - 1),
> add_ext_regions, ext_regions);
> @@ -2329,7 +2336,11 @@ static int __init construct_dom0(struct domain *d)
> if ( rc < 0 )
> return rc;
>
> - return construct_hwdom(&kinfo, NULL);
> + rc = construct_hwdom(&kinfo, NULL);
> +
> + rangeset_destroy(kinfo.xen_reg_assigned);
handle_passthrough_prop is never called for the hardware domain
> + return rc;
> }
>
> int __init construct_hwdom(struct kernel_info *kinfo,
> diff --git a/xen/arch/arm/include/asm/kernel.h
> b/xen/arch/arm/include/asm/kernel.h
> index bdc96f4c18eb..b3c2d50e1e3d 100644
> --- a/xen/arch/arm/include/asm/kernel.h
> +++ b/xen/arch/arm/include/asm/kernel.h
> @@ -50,6 +50,7 @@ struct kernel_info {
> #ifdef CONFIG_STATIC_SHM
> struct shared_meminfo shm_mem;
> #endif
> + struct rangeset *xen_reg_assigned;
>
> /* kernel entry point */
> paddr_t entry;
> --
> 2.49.0
>
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