From: Tamas K Lengyel <tamas@tklengyel.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Michal Orzel <michal.orzel@arm.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
Alexandru Isaila <aisaila@bitdefender.com>,
Petre Pircalabu <ppircalabu@bitdefender.com>,
bertrand.marquis@arm.com, wei.chen@arm.com,
Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v3 10/10] arm64: Change type of hsr, cpsr, spsr_el1 to uint64_t
Date: Wed, 5 May 2021 07:49:05 -0400 [thread overview]
Message-ID: <CABfawhneqLE4uFkQW6rDR3Yc04SsohpUcAzqz9XkY-x5KfZ3vw@mail.gmail.com> (raw)
In-Reply-To: <c5676e69-a474-d1ad-c7e9-49c03be3ab66@suse.com>
On Wed, May 5, 2021 at 4:00 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 05.05.2021 09:43, Michal Orzel wrote:
> > --- a/xen/include/public/arch-arm.h
> > +++ b/xen/include/public/arch-arm.h
> > @@ -267,10 +267,10 @@ struct vcpu_guest_core_regs
> >
> > /* Return address and mode */
> > __DECL_REG(pc64, pc32); /* ELR_EL2 */
> > - uint32_t cpsr; /* SPSR_EL2 */
> > + uint64_t cpsr; /* SPSR_EL2 */
> >
> > union {
> > - uint32_t spsr_el1; /* AArch64 */
> > + uint64_t spsr_el1; /* AArch64 */
> > uint32_t spsr_svc; /* AArch32 */
> > };
>
> This change affects, besides domctl, also default_initialise_vcpu(),
> which Arm's arch_initialise_vcpu() calls. I realize do_arm_vcpu_op()
> only allows two unrelated VCPUOP_* to pass, but then I don't
> understand why arch_initialise_vcpu() doesn't simply return e.g.
> -EOPNOTSUPP. Hence I suspect I'm missing something.
>
> > --- a/xen/include/public/domctl.h
> > +++ b/xen/include/public/domctl.h
> > @@ -38,7 +38,7 @@
> > #include "hvm/save.h"
> > #include "memory.h"
> >
> > -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000013
> > +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000014
>
> So this is to cover for the struct vcpu_guest_core_regs change.
>
> > --- a/xen/include/public/vm_event.h
> > +++ b/xen/include/public/vm_event.h
> > @@ -266,8 +266,7 @@ struct vm_event_regs_arm {
> > uint64_t ttbr1;
> > uint64_t ttbcr;
> > uint64_t pc;
> > - uint32_t cpsr;
> > - uint32_t _pad;
> > + uint64_t cpsr;
> > };
>
> Then I wonder why this isn't accompanied by a similar bump of
> VM_EVENT_INTERFACE_VERSION. I don't see you drop any checking /
> filling of the _pad field, so existing callers may pass garbage
> there, and new callers need to be prevented from looking at the
> upper half when running on an older hypervisor.
No, there is no need to bump the vm event interface version here. They
are folding the _pad into the cpsr and the structure is always zero
initialized. There is never "garbage" in the _pad field. As such there
is no change to the structure layout or anyone using it with a header
compiled on an older version. I asked them not to bump the version for
this change.
Thanks,
Tamas
next prev parent reply other threads:[~2021-05-05 11:50 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 7:42 [PATCH v3 00/10] arm64: Get rid of READ/WRITE_SYSREG32 Michal Orzel
2021-05-05 7:42 ` [PATCH v3 01/10] arm64/vfp: " Michal Orzel
2021-05-05 7:43 ` [PATCH v3 02/10] arm/domain: " Michal Orzel
2021-05-05 18:03 ` Julien Grall
2021-05-06 6:13 ` Michal Orzel
2021-05-10 17:02 ` Julien Grall
2021-05-05 7:43 ` [PATCH v3 03/10] arm: Modify type of actlr to register_t Michal Orzel
2021-05-05 18:04 ` Julien Grall
2021-05-05 7:43 ` [PATCH v3 04/10] arm/gic: Remove member hcr of structure gic_v3 Michal Orzel
2021-05-05 7:43 ` [PATCH v3 05/10] arm/gic: Get rid of READ/WRITE_SYSREG32 Michal Orzel
2021-05-05 18:06 ` Julien Grall
2021-05-05 7:43 ` [PATCH v3 06/10] arm/p2m: " Michal Orzel
2021-05-05 7:43 ` [PATCH v3 07/10] xen/arm: Always access SCTLR_EL2 using READ/WRITE_SYSREG() Michal Orzel
2021-05-05 18:07 ` Julien Grall
2021-05-05 7:43 ` [PATCH v3 08/10] arm/page: Get rid of READ/WRITE_SYSREG32 Michal Orzel
2021-05-05 7:43 ` [PATCH v3 09/10] arm/time,vtimer: " Michal Orzel
2021-05-05 7:43 ` [PATCH v3 10/10] arm64: Change type of hsr, cpsr, spsr_el1 to uint64_t Michal Orzel
2021-05-05 8:00 ` Jan Beulich
2021-05-05 11:49 ` Tamas K Lengyel [this message]
2021-05-11 6:37 ` Michal Orzel
2021-05-12 17:59 ` Julien Grall
2021-05-12 18:14 ` Andrew Cooper
2021-05-17 7:01 ` Jan Beulich
2021-05-17 16:03 ` Julien Grall
2021-05-21 6:33 ` Michal Orzel
2021-05-21 7:07 ` Jan Beulich
2021-06-07 13:16 ` Michal Orzel
2021-06-07 13:31 ` Julien Grall
2021-07-01 8:19 ` Michal Orzel
2021-07-03 14:42 ` Julien Grall
2021-05-10 17:19 ` [PATCH v3 00/10] arm64: Get rid of READ/WRITE_SYSREG32 Julien Grall
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