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Re: [PATCH v6 4/7] xen/arm: configure dom0less domain for enabling xenstore after boot

To: Stefano Stabellini <sstabellini@xxxxxxxxxx>

From: Rahul Singh <Rahul.Singh@xxxxxxx>

Date: Tue, 10 May 2022 16:30:45 +0000

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Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, "julien@xxxxxxx" <julien@xxxxxxx>, "Volodymyr_Babchuk@xxxxxxxx" <Volodymyr_Babchuk@xxxxxxxx>, Luca Miccio <lucmiccio@xxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>, "jbeulich@xxxxxxxx" <jbeulich@xxxxxxxx>

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Thread-topic: [PATCH v6 4/7] xen/arm: configure dom0less domain for enabling xenstore after boot

Hi Stefano, > On 5 May 2022, at 1:16 am, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote: > > From: Luca Miccio <lucmiccio@xxxxxxxxx> > > Export evtchn_alloc_unbound and make it __must_check. > > If "xen,enhanced" is enabled, then add to dom0less domains: > > - the hypervisor node in device tree > - the xenstore event channel > > The xenstore event channel is also used for the first notification to > let the guest know that xenstore has become available. > > Signed-off-by: Luca Miccio <lucmiccio@xxxxxxxxx> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx> > Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx> > CC: Julien Grall <julien@xxxxxxx> > CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx> > CC: Bertrand Marquis <bertrand.marquis@xxxxxxx> > CC: jbeulich@xxxxxxxx > > --- > Changes in v5: > - merge with "xen: export evtchn_alloc_unbound" > - __must_check > > Changes in v3: > - use evtchn_alloc_unbound > > Changes in v2: > - set HVM_PARAM_STORE_PFN to ~0ULL at domain creation > - in alloc_xenstore_evtchn do not call _evtchn_alloc_unbound > > xen: export evtchn_alloc_unbound > > It will be used during dom0less domains construction. > > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx> > --- > xen/arch/arm/domain_build.c | 37 +++++++++++++++++++++++++++++++++++++ > xen/common/event_channel.c | 2 +- > xen/include/xen/event.h | 3 +++ > 3 files changed, 41 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c > index 016f56a99f..bb430f2189 100644 > --- a/xen/arch/arm/domain_build.c > +++ b/xen/arch/arm/domain_build.c > @@ -27,6 +27,7 @@ > #include <asm/setup.h> > #include <asm/cpufeature.h> > #include <asm/domain_build.h> > +#include <xen/event.h> > > #include <xen/irq.h> > #include <xen/grant_table.h> > @@ -2810,6 +2811,8 @@ static int __init prepare_dtb_domU(struct domain *d, > struct kernel_info *kinfo) > int ret; > > kinfo->phandle_gic = GUEST_PHANDLE_GIC; > + kinfo->gnttab_start = GUEST_GNTTAB_BASE; > + kinfo->gnttab_size = GUEST_GNTTAB_SIZE; > > addrcells = GUEST_ROOT_ADDRESS_CELLS; > sizecells = GUEST_ROOT_SIZE_CELLS; > @@ -2884,6 +2887,13 @@ static int __init prepare_dtb_domU(struct domain *d, > struct kernel_info *kinfo) > goto err; > } > > + if ( kinfo->dom0less_enhanced ) > + { > + ret = make_hypervisor_node(d, kinfo, addrcells, sizecells); > + if ( ret ) > + goto err; > + } > + > ret = fdt_end_node(kinfo->fdt); > if ( ret < 0 ) > goto err; > @@ -3150,6 +3160,25 @@ static int __init construct_domain(struct domain *d, > struct kernel_info *kinfo) > return 0; > } > > +static int __init alloc_xenstore_evtchn(struct domain *d) > +{ > + evtchn_alloc_unbound_t alloc; > + int rc; > + > + alloc.dom = d->domain_id; > + alloc.remote_dom = hardware_domain->domain_id; I tried to test the patch series with two dom0less domUs without dom0 and oberved the below error. This error is because there is no hardware_domain in that case. (XEN) Data Abort Trap. Syndrome=0x6 (XEN) Walking Hypervisor VA 0x0 on CPU0 via TTBR 0x00000000f91f5000 (XEN) 0TH[0x0] = 0x00000000f91f4f7f (XEN) 1ST[0x0] = 0x00000000f91f1f7f (XEN) 2ND[0x0] = 0x0000000000000000 (XEN) CPU0: Unexpected Trap: Data Abort (XEN) ----[ Xen-4.17-unstable arm64 debug=y Not tainted ]---- (XEN) CPU: 0 (XEN) PC: 00000000002e4180 domain_build.c#construct_domU+0xc90/0xd0c (XEN) LR: 00000000002e4178 (XEN) SP: 000000000031e450 (XEN) CPSR: 0000000060000249 MODE:64-bit EL2h (Hypervisor, handler) (XEN) X0: 0000000000000000 X1: 0000000000000000 X2: 0000000000000000 (XEN) X3: 0000000000000005 X4: 0000000000000000 X5: 0000000000000028 (XEN) X6: 0000000000000080 X7: fefefefefefeff09 X8: 7f7f7f7f7f7f7f7f (XEN) X9: ff6f606c2c68726c X10: 7f7f7f7f7f7f7f7f X11: 0101010101010101 (XEN) X12: 0000000000000008 X13: 00000000002ca000 X14: 00000000002cb000 (XEN) X15: 6db6db6db6db6db7 X16: fffffff800000000 X17: 0000000000000001 (XEN) X18: 0180000000000000 X19: 0000800763a34000 X20: 0000000000000000 (XEN) X21: 000000000031e4c0 X22: 000000000031e4d0 X23: 0000000000000003 (XEN) X24: 000000000031fdfc X25: 0000008400000000 X26: 0000000000000021 (XEN) X27: 0000000000300d08 X28: 00000000003fe97f FP: 000000000031e450 (XEN) (XEN) VTCR_EL2: 00000000800d3590 (XEN) VTTBR_EL2: 00000083e3a67000 (XEN) (XEN) SCTLR_EL2: 0000000030cd183d (XEN) HCR_EL2: 0000000080000039 (XEN) TTBR0_EL2: 00000000f91f5000 (XEN) (XEN) ESR_EL2: 0000000096000006 (XEN) HPFAR_EL2: 0000000000000000 (XEN) FAR_EL2: 0000000000000000 (XEN) (XEN) Xen stack trace from sp=000000000031e450: (XEN) 000000000031fda0 00000000002e5484 0000800763ff2390 00000000002f1ae0 (XEN) 00000000002c98c8 000000000031fde0 0000000000000003 000000000031fdfc (XEN) 0000008400000000 0000000000000021 0000000000300d08 00000000003fe97f (XEN) 00c2010000000000 000000000031e4e0 0000000000000000 00000000040f0000 (XEN) 0000002200000001 0010000000000000 0000020300000000 0000000100000000 (XEN) 00000000000c0000 0000000000000000 0000000000000001 0000800763a34000 (XEN) 0000800763a0c000 0000000000000000 0000000000000001 00000000a0000000 (XEN) 0000000030000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) 0000000000000000 0000000000000000 0000000000000000 0000000000000000 (XEN) Xen call trace: (XEN) [<00000000002e4180>] domain_build.c#construct_domU+0xc90/0xd0c (PC) (XEN) [<00000000002e4178>] domain_build.c#construct_domU+0xc88/0xd0c (LR) (XEN) [<00000000002e5484>] create_domUs+0xb4/0x1e8 (XEN) [<00000000002e999c>] start_xen+0xaf0/0xbe8 (XEN) [<00000000002001a0>] arm64/head.o#primary_switched+0xc/0x1c (XEN) (XEN) (XEN) **************************************** (XEN) Panic on CPU 0: (XEN) CPU0: Unexpected Trap: Data Abort (XEN) **************************************** > + rc = evtchn_alloc_unbound(&alloc); > + if ( rc ) > + { > + printk("Failed allocating event channel for domain\n"); > + return rc; > + } > + > + d->arch.hvm.params[HVM_PARAM_STORE_EVTCHN] = alloc.port; > + > + return 0; > +} > + > static int __init construct_domU(struct domain *d, > const struct dt_device_node *node) > { > @@ -3214,6 +3243,14 @@ static int __init construct_domU(struct domain *d, > if ( rc < 0 ) > return rc; > > + if ( kinfo.dom0less_enhanced ) I think we need to do something like this to fix the error. if ( hardware_domain && kinfo.dom0less_enhanced ) { } > + { > + rc = alloc_xenstore_evtchn(d); > + if ( rc < 0 ) > + return rc; > + d->arch.hvm.params[HVM_PARAM_STORE_PFN] = ~0ULL; > + } > + > return rc; > } Regards, Rahul

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