From: Julien Grall <julien.grall@arm.com> To: Jan Beulich <JBeulich@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wei.liu2@citrix.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>, oleksandr_tyshchenko@epam.com, xen-devel <xen-devel@lists.xenproject.org>, "andrii_anisov@epam.com" <andrii_anisov@epam.com>, Roger Pau Monne <roger.pau@citrix.com> Subject: Re: [PATCH 09/14] xen: Introduce HAS_M2P config and use to protect mfn_to_gmfn call Date: Fri, 10 May 2019 15:34:48 +0100 [thread overview] Message-ID: <16cea000-3b02-08f6-4b0e-2df1024ed245@arm.com> (raw) In-Reply-To: <5CD58873020000780022D9FC@prv1-mh.provo.novell.com> Hi Jan, On 10/05/2019 15:19, Jan Beulich wrote: >>>> On 10.05.19 at 16:04, <julien.grall@arm.com> wrote: >> On 10/05/2019 14:45, Jan Beulich wrote: >>>>>> On 10.05.19 at 15:41, <julien.grall@arm.com> wrote: >>>> The point here, we keep within the hypervisor the idea of what's valid or >>>> invalid. This allows us more flexibility on the value here (imagine we decide to >>>> change the value of GFN_INVALID in the future...). >>> >>> Exactly, and hence INVALID_GFN should not become visible to the >>> outside. Hence my request to use an all-ones value here. >> It is only visible if you put an exact value in the documentation. Your >> suggestion is to put a exactly value and I would rather not see that. > > I did specifically suggest to _not_ store INVALID_GFN here, but to > store 64-bit bits of ones. Note the difference between the two on > 32-bit Arm. Your point of having an exact value is only useful if you want to toolstack to silently ignore the missing frame and avoid a call. The former is pretty much wrong as if you were trying to read the frame then most likely you wanted to access it. So a message makes sense here. For the latter, avoiding the call is only going to save you a couple of cycles in a likely cold path. You really don't need to give an exact (including say all ones). You only need to say that the address return may not be mappable. The toolstack will try to map it and fail. That's not a big deal. Anyway, I will wait and see what's the view from the tools maintainer. > > Preferably yes; depends on how exactly you code the assertion. > If you follow the if()-ASSERT_UNREACHABLE()-return style we've > been using elsewhere, then no matter how you place the #else > or #endif the printk() will be compiled out. I will have a look. Cheers, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
WARNING: multiple messages have this Message-ID (diff)
From: Julien Grall <julien.grall@arm.com> To: Jan Beulich <JBeulich@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wei.liu2@citrix.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>, oleksandr_tyshchenko@epam.com, xen-devel <xen-devel@lists.xenproject.org>, "andrii_anisov@epam.com" <andrii_anisov@epam.com>, Roger Pau Monne <roger.pau@citrix.com> Subject: Re: [Xen-devel] [PATCH 09/14] xen: Introduce HAS_M2P config and use to protect mfn_to_gmfn call Date: Fri, 10 May 2019 15:34:48 +0100 [thread overview] Message-ID: <16cea000-3b02-08f6-4b0e-2df1024ed245@arm.com> (raw) Message-ID: <20190510143448.1o0rTVvcqBM_U637F4EeXrtafHqq0_Tq2tTImcqJLe0@z> (raw) In-Reply-To: <5CD58873020000780022D9FC@prv1-mh.provo.novell.com> Hi Jan, On 10/05/2019 15:19, Jan Beulich wrote: >>>> On 10.05.19 at 16:04, <julien.grall@arm.com> wrote: >> On 10/05/2019 14:45, Jan Beulich wrote: >>>>>> On 10.05.19 at 15:41, <julien.grall@arm.com> wrote: >>>> The point here, we keep within the hypervisor the idea of what's valid or >>>> invalid. This allows us more flexibility on the value here (imagine we decide to >>>> change the value of GFN_INVALID in the future...). >>> >>> Exactly, and hence INVALID_GFN should not become visible to the >>> outside. Hence my request to use an all-ones value here. >> It is only visible if you put an exact value in the documentation. Your >> suggestion is to put a exactly value and I would rather not see that. > > I did specifically suggest to _not_ store INVALID_GFN here, but to > store 64-bit bits of ones. Note the difference between the two on > 32-bit Arm. Your point of having an exact value is only useful if you want to toolstack to silently ignore the missing frame and avoid a call. The former is pretty much wrong as if you were trying to read the frame then most likely you wanted to access it. So a message makes sense here. For the latter, avoiding the call is only going to save you a couple of cycles in a likely cold path. You really don't need to give an exact (including say all ones). You only need to say that the address return may not be mappable. The toolstack will try to map it and fail. That's not a big deal. Anyway, I will wait and see what's the view from the tools maintainer. > > Preferably yes; depends on how exactly you code the assertion. > If you follow the if()-ASSERT_UNREACHABLE()-return style we've > been using elsewhere, then no matter how you place the #else > or #endif the printk() will be compiled out. I will have a look. Cheers, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-05-10 14:34 UTC|newest] Thread overview: 154+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-07 15:14 [PATCH 00/14] xen/arm: Properly disable M2P on Arm Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 01/14] xen/arm: Use mfn_to_pdx instead of pfn_to_pdx when possible Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-09 17:50 ` Stefano Stabellini 2019-05-09 17:50 ` [Xen-devel] " Stefano Stabellini 2019-05-07 15:14 ` [PATCH 02/14] xen/x86: Constify the parameter "d" in mfn_to_gfn Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 03/14] xen/x86: Make mfn_to_gfn typesafe Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-10 11:35 ` Jan Beulich 2019-05-10 11:35 ` [Xen-devel] " Jan Beulich 2019-05-10 13:02 ` Julien Grall 2019-05-10 13:02 ` [Xen-devel] " Julien Grall 2019-05-10 13:24 ` Jan Beulich 2019-05-10 13:24 ` [Xen-devel] " Jan Beulich 2019-05-10 13:25 ` Julien Grall 2019-05-10 13:25 ` [Xen-devel] " Julien Grall 2019-05-20 15:13 ` Julien Grall 2019-05-20 15:13 ` [Xen-devel] " Julien Grall 2019-05-28 17:29 ` George Dunlap 2019-05-28 17:29 ` [Xen-devel] " George Dunlap 2019-05-29 11:39 ` Julien Grall 2019-05-29 11:39 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 04/14] xen/x86: Use mfn_to_gfn rather than mfn_to_gmfn Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-10 12:15 ` Jan Beulich 2019-05-10 12:15 ` [Xen-devel] " Jan Beulich 2019-05-10 13:07 ` Julien Grall 2019-05-10 13:07 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 05/14] xen/grant-table: Make arch specific macros typesafe Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-09 17:54 ` Stefano Stabellini 2019-05-09 17:54 ` [Xen-devel] " Stefano Stabellini 2019-05-07 15:14 ` [PATCH 06/14] xen: Convert hotplug page function to use typesafe MFN Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-09 18:01 ` Stefano Stabellini 2019-05-09 18:01 ` [Xen-devel] " Stefano Stabellini 2019-05-09 18:10 ` Julien Grall 2019-05-09 18:10 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 07/14] xen: Convert is_xen_fixed_mfn " Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-24 15:16 ` George Dunlap 2019-05-24 15:16 ` [Xen-devel] " George Dunlap 2019-05-07 15:14 ` [PATCH 08/14] xen: Convert is_xen_heap_mfn " Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-24 15:15 ` George Dunlap 2019-05-24 15:15 ` [Xen-devel] " George Dunlap 2019-05-07 15:14 ` [PATCH 09/14] xen: Introduce HAS_M2P config and use to protect mfn_to_gmfn call Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-09 18:06 ` Stefano Stabellini 2019-05-09 18:06 ` [Xen-devel] " Stefano Stabellini 2019-05-09 18:12 ` Julien Grall 2019-05-09 18:12 ` [Xen-devel] " Julien Grall 2019-05-09 18:16 ` Stefano Stabellini 2019-05-09 18:16 ` [Xen-devel] " Stefano Stabellini 2019-05-09 18:29 ` Julien Grall 2019-05-09 18:29 ` [Xen-devel] " Julien Grall 2019-05-09 19:49 ` Stefano Stabellini 2019-05-09 19:49 ` [Xen-devel] " Stefano Stabellini 2019-05-10 12:31 ` Jan Beulich 2019-05-10 12:31 ` [Xen-devel] " Jan Beulich 2019-05-10 13:22 ` Julien Grall 2019-05-10 13:22 ` [Xen-devel] " Julien Grall 2019-05-10 13:32 ` Jan Beulich 2019-05-10 13:32 ` [Xen-devel] " Jan Beulich 2019-05-10 13:41 ` Julien Grall 2019-05-10 13:41 ` [Xen-devel] " Julien Grall 2019-05-10 13:45 ` Jan Beulich 2019-05-10 13:45 ` [Xen-devel] " Jan Beulich 2019-05-10 14:04 ` Julien Grall 2019-05-10 14:04 ` [Xen-devel] " Julien Grall 2019-05-10 14:19 ` Jan Beulich 2019-05-10 14:19 ` [Xen-devel] " Jan Beulich 2019-05-10 14:34 ` Julien Grall [this message] 2019-05-10 14:34 ` Julien Grall 2019-05-22 16:03 ` Julien Grall 2019-05-22 16:03 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 10/14] xen: Remove mfn_to_gmfn macro Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 11/14] xen/x86: mm: Re-implement set_gpfn_from_mfn() as a static inline function Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-10 12:43 ` Jan Beulich 2019-05-10 12:43 ` [Xen-devel] " Jan Beulich 2019-05-10 13:27 ` Julien Grall 2019-05-10 13:27 ` [Xen-devel] " Julien Grall 2019-05-10 13:35 ` Jan Beulich 2019-05-10 13:35 ` [Xen-devel] " Jan Beulich 2019-05-10 13:41 ` Julien Grall 2019-05-10 13:41 ` [Xen-devel] " Julien Grall 2019-05-10 13:48 ` Jan Beulich 2019-05-10 13:48 ` [Xen-devel] " Jan Beulich 2019-05-10 14:05 ` Julien Grall 2019-05-10 14:05 ` [Xen-devel] " Julien Grall 2019-05-10 14:21 ` Jan Beulich 2019-05-10 14:21 ` [Xen-devel] " Jan Beulich 2019-05-10 14:48 ` Julien Grall 2019-05-10 14:48 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 12/14] xen/x86: pv: Convert update_intpte() to use typesafe MFN Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-10 12:54 ` Jan Beulich 2019-05-10 12:54 ` [Xen-devel] " Jan Beulich 2019-05-10 13:28 ` Julien Grall 2019-05-10 13:28 ` [Xen-devel] " Julien Grall 2019-05-07 15:14 ` [PATCH 13/14] xen/mm: Convert {s, g}et_gpfn_from_mfn() " Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-07 20:27 ` Tamas K Lengyel 2019-05-07 20:27 ` [Xen-devel] " Tamas K Lengyel 2019-05-09 18:19 ` Stefano Stabellini 2019-05-09 18:19 ` [Xen-devel] " Stefano Stabellini 2019-05-10 13:21 ` Jan Beulich 2019-05-10 13:21 ` [Xen-devel] " Jan Beulich 2019-05-10 13:27 ` Andrew Cooper 2019-05-10 13:27 ` [Xen-devel] " Andrew Cooper 2019-05-10 13:34 ` Julien Grall 2019-05-10 13:34 ` [Xen-devel] " Julien Grall 2019-05-10 13:41 ` Jan Beulich 2019-05-10 13:41 ` [Xen-devel] " Jan Beulich 2019-05-10 13:46 ` Julien Grall 2019-05-10 13:46 ` [Xen-devel] " Julien Grall 2019-05-10 14:02 ` Jan Beulich 2019-05-10 14:02 ` [Xen-devel] " Jan Beulich 2019-05-10 14:05 ` Andrew Cooper 2019-05-10 14:05 ` [Xen-devel] " Andrew Cooper 2019-05-10 14:08 ` Julien Grall 2019-05-10 14:08 ` [Xen-devel] " Julien Grall 2019-05-10 14:09 ` Andrew Cooper 2019-05-10 14:09 ` [Xen-devel] " Andrew Cooper 2019-05-10 14:14 ` Jan Beulich 2019-05-10 14:14 ` [Xen-devel] " Jan Beulich 2019-05-10 14:27 ` Andrew Cooper 2019-05-10 14:27 ` [Xen-devel] " Andrew Cooper 2019-05-24 16:24 ` George Dunlap 2019-05-24 16:24 ` [Xen-devel] " George Dunlap 2019-05-29 16:27 ` Julien Grall 2019-05-29 16:27 ` [Xen-devel] " Julien Grall 2019-05-29 16:29 ` George Dunlap 2019-05-29 16:29 ` [Xen-devel] " George Dunlap 2019-05-24 16:35 ` George Dunlap 2019-05-24 16:35 ` [Xen-devel] " George Dunlap 2019-05-07 15:14 ` [PATCH 14/14] xen/mm: Provide dummy M2P-related helpers when !CONFIG_HAVE_M2P Julien Grall 2019-05-07 15:14 ` [Xen-devel] " Julien Grall 2019-05-09 18:20 ` Stefano Stabellini 2019-05-09 18:20 ` [Xen-devel] " Stefano Stabellini 2019-05-10 13:28 ` Jan Beulich 2019-05-10 13:28 ` [Xen-devel] " Jan Beulich 2019-05-10 13:29 ` Julien Grall 2019-05-10 13:29 ` [Xen-devel] " Julien Grall 2019-05-10 13:37 ` Jan Beulich 2019-05-10 13:37 ` [Xen-devel] " Jan Beulich 2019-05-10 13:38 ` Julien Grall 2019-05-10 13:38 ` [Xen-devel] " Julien Grall 2019-05-24 16:51 ` George Dunlap 2019-05-24 16:51 ` [Xen-devel] " George Dunlap
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