From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: "Elena Ufimtseva" <elena.ufimtseva@oracle.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
"George Dunlap" <george.dunlap@citrix.com>,
"Julien Grall" <julien@xen.org>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Cheyenne Wills" <cheyenne.wills@gmail.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2] xen: fix XEN_DOMCTL_gdbsx_guestmemio crash
Date: Tue, 19 Apr 2022 12:31:17 +0200 [thread overview]
Message-ID: <5c884c16-ab97-f4db-2e8c-c34586fa0e81@suse.com> (raw)
In-Reply-To: <20220419101850.3045-1-jgross@suse.com>
On 19.04.2022 12:18, Juergen Gross wrote:
> A hypervisor built without CONFIG_GDBSX will crash in case the
> XEN_DOMCTL_gdbsx_guestmemio domctl is being called, as the call will
> end up in iommu_do_domctl() with d == NULL:
>
> (XEN) CPU: 6
> (XEN) RIP: e008:[<ffff82d040269984>] iommu_do_domctl+0x4/0x30
> (XEN) RFLAGS: 0000000000010202 CONTEXT: hypervisor (d0v0)
> (XEN) rax: 00000000000003e8 rbx: ffff830856277ef8 rcx: ffff830856277fff
> ...
> (XEN) Xen call trace:
> (XEN) [<ffff82d040269984>] R iommu_do_domctl+0x4/0x30
> (XEN) [<ffff82d04035cd5f>] S arch_do_domctl+0x7f/0x2330
> (XEN) [<ffff82d040239e46>] S do_domctl+0xe56/0x1930
> (XEN) [<ffff82d040238ff0>] S do_domctl+0/0x1930
> (XEN) [<ffff82d0402f8c59>] S pv_hypercall+0x99/0x110
> (XEN) [<ffff82d0402f5161>] S arch/x86/pv/domain.c#_toggle_guest_pt+0x11/0x90
> (XEN) [<ffff82d040366288>] S lstar_enter+0x128/0x130
> (XEN)
> (XEN) Pagetable walk from 0000000000000144:
> (XEN) L4[0x000] = 0000000000000000 ffffffffffffffff
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 6:
> (XEN) FATAL PAGE FAULT
> (XEN) [error_code=0000]
> (XEN) Faulting linear address: 0000000000000144
>
> Fix this issue by modifying the interface of gdbsx_guest_mem_io() to
> take the already known domain pointer instead of the domid.
>
> Reported-by: Cheyenne Wills <cheyenne.wills@gmail.com>
> Fixes: e726a82ca0dc ("xen: make gdbsx support configurable")
> Suggested-by: Jan Beulich <jbeulich@suse.com>
> Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
with one nit (which can be taken care of while committing):
> --- a/xen/arch/x86/debug.c
> +++ b/xen/arch/x86/debug.c
> @@ -159,17 +159,11 @@ static unsigned int dbg_rw_guest_mem(struct domain *dp, unsigned long addr,
> * Returns: number of bytes remaining to be copied.
> */
> unsigned int dbg_rw_mem(unsigned long gva, XEN_GUEST_HANDLE_PARAM(void) buf,
> - unsigned int len, domid_t domid, bool toaddr,
> + unsigned int len, struct domain *d, bool toaddr,
> uint64_t pgd3)
> {
> - struct domain *d = rcu_lock_domain_by_id(domid);
> -
> - if ( d )
> - {
> - if ( !d->is_dying )
> + if ( d && !d->is_dying )
> len = dbg_rw_guest_mem(d, gva, buf, len, toaddr, pgd3);
This line now wants its indentation adjusted.
Jan
next prev parent reply other threads:[~2022-04-19 10:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-19 10:18 [PATCH v2] xen: fix XEN_DOMCTL_gdbsx_guestmemio crash Juergen Gross
2022-04-19 10:31 ` Jan Beulich [this message]
2022-04-19 10:40 ` Andrew Cooper
2022-04-19 10:51 ` Juergen Gross
2022-04-19 12:59 ` Andrew Cooper
2022-04-19 10:54 ` Jan Beulich
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