From: "Jan Beulich" <JBeulich@suse.com> To: aisaila@bitdefender.com Cc: Tamas K Lengyel <tamas@tklengyel.com>, Wei Liu <wei.liu2@citrix.com>, Razvan Cojocaru <rcojocaru@bitdefender.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Paul Durrant <paul.durrant@citrix.com>, xen-devel <xen-devel@lists.xenproject.org>, Roger Pau Monne <roger.pau@citrix.com> Subject: Re: [PATCH v4 2/2] x86/emulate: Send vm_event from emulate Date: Fri, 31 May 2019 03:16:27 -0600 [thread overview] Message-ID: <5CF0F0EB0200007800233D64@prv1-mh.provo.novell.com> (raw) In-Reply-To: <b6f3254b-2bce-ecd6-cddb-10131f075fb6@bitdefender.com> >>> On 30.05.19 at 10:59, <aisaila@bitdefender.com> wrote: >> >>> + return false; >>> + >>> + rc = hvmemul_linear_to_phys(gla, &gpa, bytes, &reps, pfec, &ctxt); >> >> As said before - I don't think it's a good idea to do the page walk >> twice: This and the pre-existing one can easily return different >> results. > > What preexisting page walk are you talking about here? Well, I'm afraid I don't know what to say (in a polite way). I'm sure you're understanding the code you try to add to, so it would seem natural to me that you can answer this question all by yourself: Since you don't remove any linear->phys translations in your patch, and since there necessarily is one prior to your patch, you adding (another) one means there are now two of them. So to answer your question directly: hvmemul_map_linear_addr() calls hvm_translate_get_page(), and hvmemul_insn_fetch() -> __hvmemul_read() -> linear_read() -> hvm_copy_from_guest_linear() -> __hvm_copy() calls hvm_translate_get_page() as well. As an aside - while I'm advocating the stripping of reply quoting that's not needed as context, you surely went too far here: You've left in place neither an indication when the mails were sent context of which is still present above, nor enough context to re-construct what function your additions go into. IOW I had to search the earlier parts of this thread to gather enough context to actually be able to reply. > I don't think > there is a way to get the gpa by passing it from somewhere. Possibly, but that's also not what I did suggest. Instead what I think you need to look into is how to restructure things, perhaps just as to the place where you insert your new code. Jan _______________________________________________ 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: "Jan Beulich" <JBeulich@suse.com> To: <aisaila@bitdefender.com> Cc: Tamas K Lengyel <tamas@tklengyel.com>, Wei Liu <wei.liu2@citrix.com>, Razvan Cojocaru <rcojocaru@bitdefender.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Paul Durrant <paul.durrant@citrix.com>, xen-devel <xen-devel@lists.xenproject.org>, Roger Pau Monne <roger.pau@citrix.com> Subject: Re: [Xen-devel] [PATCH v4 2/2] x86/emulate: Send vm_event from emulate Date: Fri, 31 May 2019 03:16:27 -0600 [thread overview] Message-ID: <5CF0F0EB0200007800233D64@prv1-mh.provo.novell.com> (raw) Message-ID: <20190531091627.Miyh-Y6SmU8MKCM-iSAjJeKC-y6vY4o7OEliuRLT3QM@z> (raw) In-Reply-To: <b6f3254b-2bce-ecd6-cddb-10131f075fb6@bitdefender.com> >>> On 30.05.19 at 10:59, <aisaila@bitdefender.com> wrote: >> >>> + return false; >>> + >>> + rc = hvmemul_linear_to_phys(gla, &gpa, bytes, &reps, pfec, &ctxt); >> >> As said before - I don't think it's a good idea to do the page walk >> twice: This and the pre-existing one can easily return different >> results. > > What preexisting page walk are you talking about here? Well, I'm afraid I don't know what to say (in a polite way). I'm sure you're understanding the code you try to add to, so it would seem natural to me that you can answer this question all by yourself: Since you don't remove any linear->phys translations in your patch, and since there necessarily is one prior to your patch, you adding (another) one means there are now two of them. So to answer your question directly: hvmemul_map_linear_addr() calls hvm_translate_get_page(), and hvmemul_insn_fetch() -> __hvmemul_read() -> linear_read() -> hvm_copy_from_guest_linear() -> __hvm_copy() calls hvm_translate_get_page() as well. As an aside - while I'm advocating the stripping of reply quoting that's not needed as context, you surely went too far here: You've left in place neither an indication when the mails were sent context of which is still present above, nor enough context to re-construct what function your additions go into. IOW I had to search the earlier parts of this thread to gather enough context to actually be able to reply. > I don't think > there is a way to get the gpa by passing it from somewhere. Possibly, but that's also not what I did suggest. Instead what I think you need to look into is how to restructure things, perhaps just as to the place where you insert your new code. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-05-31 9:16 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-20 12:55 [PATCH v4 1/2] x86/emulate: Move hvmemul_linear_to_phys Alexandru Stefan ISAILA 2019-05-20 12:55 ` [Xen-devel] " Alexandru Stefan ISAILA 2019-05-20 12:55 ` [PATCH v4 2/2] x86/emulate: Send vm_event from emulate Alexandru Stefan ISAILA 2019-05-20 12:55 ` [Xen-devel] " Alexandru Stefan ISAILA 2019-05-22 9:56 ` Jan Beulich 2019-05-22 9:56 ` [Xen-devel] " Jan Beulich 2019-05-22 12:59 ` Alexandru Stefan ISAILA 2019-05-22 12:59 ` [Xen-devel] " Alexandru Stefan ISAILA 2019-05-22 13:34 ` Jan Beulich 2019-05-22 13:34 ` [Xen-devel] " Jan Beulich 2019-05-22 13:50 ` Alexandru Stefan ISAILA 2019-05-22 13:50 ` [Xen-devel] " Alexandru Stefan ISAILA 2019-05-22 13:57 ` Jan Beulich 2019-05-22 13:57 ` [Xen-devel] " Jan Beulich 2019-05-30 8:59 ` Alexandru Stefan ISAILA 2019-05-30 8:59 ` [Xen-devel] " Alexandru Stefan ISAILA 2019-05-31 9:16 ` Jan Beulich [this message] 2019-05-31 9:16 ` Jan Beulich 2019-05-22 13:13 ` [PATCH v4 1/2] x86/emulate: Move hvmemul_linear_to_phys Paul Durrant 2019-05-22 13:13 ` [Xen-devel] " Paul Durrant 2019-05-22 13:55 ` George Dunlap 2019-05-22 13:55 ` [Xen-devel] " George Dunlap
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