Re: [Xen-devel] [PATCH v13 0/4] add per-domain IOMMU control

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Oleksandr <olekstysh@xxxxxxxxx>
> Sent: 25 September 2019 16:50
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; 'Jan Beulich' <jbeulich@xxxxxxxx>
> Cc: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>; Stefano Stabellini 
> <sstabellini@xxxxxxxxxx>; Wei Liu
> <wl@xxxxxxx>; KonradRzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; David Scott <dave@xxxxxxxxxx>; Tim (Xen.org) 
> <tim@xxxxxxx>; George Dunlap
> <George.Dunlap@xxxxxxxxxx>; Tamas K Lengyel <tamas@xxxxxxxxxxxxx>; Ian Jackson
> <Ian.Jackson@xxxxxxxxxx>; Anthony Perard <anthony.perard@xxxxxxxxxx>; 
> xen-devel@xxxxxxxxxxxxxxxxxxxx;
> Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>; Roger Pau Monne 
> <roger.pau@xxxxxxxxxx>; Julien Grall
> <julien.grall@xxxxxxx>
> Subject: Re: [Xen-devel] [PATCH v13 0/4] add per-domain IOMMU control
> 
> 
> [CC Julien]
> 
> 
> Hi Paul
> 
> I may mistake, but looks like
> 
> 80ff3d338dc93260b41ffeeebb0f852c2edef9ce iommu: tidy up
> iommu_use_hap_pt() and need_iommu_pt_sync() macros
> 
> triggers ASSERT_UNREACHABLE on Arm if no IOMMU has been found (I built
> with my platform's IOMMU driver disabled: # CONFIG_IPMMU_VMSA is not set) .
> 
> So, iommu_setup() calls clear_iommu_hap_pt_share() with
> iommu_hap_pt_share being set (CONFIG_IOMMU_FORCE_PT_SHARE=y) which,
> actually, triggers ASSERT.
> 

Here a minimal patch, leaving 'force pt share' in place. Does this avoid the 
problem?

---8<---
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index e8763c7fdf..f88a285e7f 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -268,9 +268,11 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) 
u_sysctl)
         pi->max_mfn = get_upper_mfn_bound();
         arch_do_physinfo(pi);
         if ( iommu_enabled )
+        {
             pi->capabilities |= XEN_SYSCTL_PHYSCAP_directio;
-        if ( iommu_hap_pt_share )
-            pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
+            if ( iommu_hap_pt_share )
+                pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
+        }

         if ( copy_to_guest(u_sysctl, op, 1) )
             ret = -EFAULT;
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 7c3003f3f1..6a10a24128 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -68,8 +68,6 @@ static inline void clear_iommu_hap_pt_share(void)
 {
 #ifndef iommu_hap_pt_share
     iommu_hap_pt_share = false;
-#elif iommu_hap_pt_share
-    ASSERT_UNREACHABLE();
 #endif
 }
---8<---

  Paul

> ...
> 
> 
> (XEN) Assertion 'unreachable' failed at
> ...ild-workspace/build/xen/xen/include/xen/iommu.h:72
> (XEN) ----[ Xen-4.13-unstable  arm64  debug=y   Not tainted ]----
> (XEN) CPU:    0
> (XEN) PC:     00000000002b3ae0 iommu_setup+0xa0/0x18c
> (XEN) LR:     00000000002b3a8c
> (XEN) SP:     00000000002f7dc0
> (XEN) CPSR:   a0000249 MODE:64-bit EL2h (Hypervisor, handler)
> (XEN)      X0: 00000000002a7000  X1: 0000000000000000  X2: 2c736173656e6572
> (XEN)      X3: 0000000000000002  X4: 0000000000000001  X5: 0000000000000000
> (XEN)      X6: 0000000000000080  X7: 2b726072646d6471  X8: 7f7f7f7f7f7f7f7f
> (XEN)      X9: ff65685e6c6f7275 X10: 7f7f7f7f7f7f7f7f X11: 0101010101010101
> (XEN)     X12: 0000000000000038 X13: 0000000000280910 X14: 0000000000000020
> (XEN)     X15: 0000000000000000 X16: 00000000002a7000 X17: 00000000002a7000
> (XEN)     X18: 00000000002a7000 X19: 0000000000000000 X20: 00000000ffffffed
> (XEN)     X21: 00000000002a6380 X22: 0000000000335430 X23: 0000000000000002
> (XEN)     X24: 000000000029b1f0 X25: 00000000002d83d0 X26: 0000000048000000
> (XEN)     X27: 00000000c0000000 X28: 0000000000000001  FP: 00000000002f7dc0
> (XEN)
> (XEN)   VTCR_EL2: 80000000
> (XEN)  VTTBR_EL2: 0000000000000000
> (XEN)
> (XEN)  SCTLR_EL2: 30cd183d
> (XEN)    HCR_EL2: 0000000000000038
> (XEN)  TTBR0_EL2: 00000000781b4000
> (XEN)
> (XEN)    ESR_EL2: f2000001
> (XEN)  HPFAR_EL2: 0000000000000000
> (XEN)    FAR_EL2: 0000000000000000
> (XEN)
> (XEN) Xen stack trace from sp=00000000002f7dc0:
> (XEN)    00000000002f7de0 00000000002bdd94 0000000000000002 0000000000000002
> (XEN)    00000000bfe0b660 00000000002001b4 0000000078080000 0000000077e80000
> (XEN)    0000000048000000 0000000000000000 0000000000400000 0000000000000003
> (XEN)    0000000000000001 0000000000000000 0000000078080000 0000000048080040
> (XEN)    0000000000000000 000000000000f080 0000000048000000 0000000078000000
> (XEN)    00000000002d83c0 00000000002aa440 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000300000000 0000000000000000 00000040ffffffff
> (XEN)    0000000000000400 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)    [<00000000002b3ae0>] iommu_setup+0xa0/0x18c (PC)
> (XEN)    [<00000000002b3a8c>] iommu_setup+0x4c/0x18c (LR)
> (XEN)    [<00000000002bdd94>] start_xen+0xaa0/0xc7c
> (XEN)    [<00000000002001b4>] arm64/head.o#primary_switched+0xc/0x2c
> (XEN)
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 0:
> (XEN) Assertion 'unreachable' failed at
> ...ild-workspace/build/xen/xen/include/xen/iommu.h:72
> (XEN) ****************************************
> (XEN)
> 
> 
> --
> Regards,
> 
> Oleksandr Tyshchenko

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