From: "Roger Pau Monné" <roger.pau@citrix.com> To: Chao Gao <chao.gao@intel.com> Cc: xen-devel@lists.xenproject.org, Jan Beulich <jbeulich@suse.com>, Ashok Raj <ashok.raj@intel.com>, Wei Liu <wl@xen.org>, Andrew Cooper <andrew.cooper3@citrix.com> Subject: Re: [Xen-devel] [PATCH v9 12/15] microcode: reduce memory allocation and copy when creating a patch Date: Mon, 26 Aug 2019 10:11:03 +0200 Message-ID: <20190826081103.hb5diw7brmnbiwbv@Air-de-Roger> (raw) In-Reply-To: <20190826070320.GA11910@gao-cwp> On Mon, Aug 26, 2019 at 03:03:22PM +0800, Chao Gao wrote: > On Fri, Aug 23, 2019 at 10:11:21AM +0200, Roger Pau Monné wrote: > >On Mon, Aug 19, 2019 at 09:25:25AM +0800, Chao Gao wrote: > >> To create a microcode patch from a vendor-specific update, > >> allocate_microcode_patch() copied everything from the update. > >> It is not efficient. Essentially, we just need to go through > >> ucodes in the blob, find the one with the newest revision and > >> install it into the microcode_patch. In the process, buffers > >> like mc_amd, equiv_cpu_table (on AMD side), and mc (on Intel > >> side) can be reused. microcode_patch now is allocated after > >> it is sure that there is a matching ucode. > > > >Oh, I think this answers my question on a previous patch. > > > >For future series it would be nice to avoid so many rewrites in the > >same series, alloc_microcode_patch is already modified in a previous > >patch, just to be removed here. It also makes it harder to follow > >what's going on. > > Got it. This patch is added in this new version. And some trivial > patches already got reviewed-by. So I don't merge it with them. > > >> while ( (error = get_ucode_from_buffer_amd(mc_amd, buf, bufsize, > >> &offset)) == 0 ) > >> { > >> - struct microcode_patch *new_patch = alloc_microcode_patch(mc_amd); > >> - > >> - if ( IS_ERR(new_patch) ) > >> - { > >> - error = PTR_ERR(new_patch); > >> - break; > >> - } > >> - > >> /* > >> - * If the new patch covers current CPU, compare patches and store the > >> + * If the new ucode covers current CPU, compare ucodes and store the > >> * one with higher revision. > >> */ > >> - if ( (microcode_fits(new_patch->mc_amd) != MIS_UCODE) && > >> - (!patch || (compare_patch(new_patch, patch) == NEW_UCODE)) ) > >> +#define REV_ID(mpb) (((struct microcode_header_amd *)(mpb))->processor_rev_id) > >> + if ( (microcode_fits(mc_amd) != MIS_UCODE) && > >> + (!saved || (REV_ID(mc_amd->mpb) > REV_ID(saved))) ) > >> +#undef REV_ID > >> { > >> - struct microcode_patch *tmp = patch; > >> - > >> - patch = new_patch; > >> - new_patch = tmp; > >> + xfree(saved); > >> + saved = mc_amd->mpb; > >> + saved_size = mc_amd->mpb_size; > >> } > >> - > >> - if ( new_patch ) > >> - microcode_free_patch(new_patch); > >> + else > >> + xfree(mc_amd->mpb); > > It might be better to move 'mc_amd->mpb = NULL' here. > > >> > >> if ( offset >= bufsize ) > >> break; > >> @@ -593,9 +548,25 @@ static struct microcode_patch *cpu_request_microcode(const void *buf, > >> *(const uint32_t *)(buf + offset) == UCODE_MAGIC ) > >> break; > >> } > >> - xfree(mc_amd->mpb); > >> - xfree(mc_amd->equiv_cpu_table); > >> - xfree(mc_amd); > >> + > >> + if ( saved ) > >> + { > >> + mc_amd->mpb = saved; > >> + mc_amd->mpb_size = saved_size; > >> + patch = xmalloc(struct microcode_patch); > >> + if ( patch ) > >> + patch->mc_amd = mc_amd; > >> + else > >> + { > >> + free_patch(mc_amd); > >> + error = -ENOMEM; > >> + } > >> + } > >> + else > >> + { > >> + mc_amd->mpb = NULL; > > > >What's the point in setting mpb to NULL if you are just going to free > >mc_amd below? > > To avoid double free here. mc_amd->mpb is always freed or saved. > And here we want to free mc_amd itself and mc_amd->equiv_cpu_table. But there's no chance of a double free here, since you are freeing mc_amd in the line below after setting mpb = NULL. I think it would make sense to set mpb = NULL after freeing it inside the loop. With that you can add my: Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> > > > >Also, I'm not sure I understand why you need to free mc_amd, isn't > >this buff memory that should be freed by the caller? > > But mc_amd is allocated in this function. > > > > >ie: in the Intel counterpart below you don't seem to free the mc > >cursor used for the get_next_ucode_from_buffer loop. > > 'mc' is saved if it is newer than current patch stored in 'saved'. > Otherwise 'mc' is freed immediately. So we don't need to free it > again after the while loop. Ack, thanks! _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply index Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-19 1:25 [Xen-devel] [PATCH v9 00/15] improve late microcode loading Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 01/15] microcode/intel: extend microcode_update_match() Chao Gao 2019-08-28 15:12 ` Jan Beulich 2019-08-29 7:15 ` Chao Gao 2019-08-29 7:14 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 02/15] microcode/amd: fix memory leak Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 03/15] microcode/amd: distinguish old and mismatched ucode in microcode_fits() Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 04/15] microcode: introduce a global cache of ucode patch Chao Gao 2019-08-22 11:11 ` Roger Pau Monné 2019-08-28 15:21 ` Jan Beulich 2019-08-29 10:18 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 05/15] microcode: clean up microcode_resume_cpu Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 06/15] microcode: remove struct ucode_cpu_info Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 07/15] microcode: remove pointless 'cpu' parameter Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 08/15] microcode/amd: call svm_host_osvw_init() in common code Chao Gao 2019-08-22 13:08 ` Roger Pau Monné 2019-08-28 15:26 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 09/15] microcode: pass a patch pointer to apply_microcode() Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 10/15] microcode: split out apply_microcode() from cpu_request_microcode() Chao Gao 2019-08-22 13:59 ` Roger Pau Monné 2019-08-29 10:06 ` Jan Beulich 2019-08-30 3:22 ` Chao Gao 2019-08-30 7:25 ` Jan Beulich 2019-08-29 10:19 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 11/15] microcode: unify loading update during CPU resuming and AP wakeup Chao Gao 2019-08-22 14:10 ` Roger Pau Monné 2019-08-22 16:44 ` Chao Gao 2019-08-23 9:09 ` Roger Pau Monné 2019-08-29 7:37 ` Chao Gao 2019-08-29 8:16 ` Roger Pau Monné 2019-08-29 10:26 ` Jan Beulich 2019-08-29 10:29 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 12/15] microcode: reduce memory allocation and copy when creating a patch Chao Gao 2019-08-23 8:11 ` Roger Pau Monné 2019-08-26 7:03 ` Chao Gao 2019-08-26 8:11 ` Roger Pau Monné [this message] 2019-08-29 10:47 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 13/15] x86/microcode: Synchronize late microcode loading Chao Gao 2019-08-19 10:27 ` Sergey Dyasli 2019-08-19 14:49 ` Chao Gao 2019-08-29 12:06 ` Jan Beulich 2019-08-30 3:30 ` Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 14/15] microcode: remove microcode_update_lock Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 15/15] microcode: block #NMI handling when loading an ucode Chao Gao 2019-08-23 8:46 ` Sergey Dyasli 2019-08-26 8:07 ` Chao Gao 2019-08-27 4:52 ` Chao Gao 2019-08-28 8:52 ` Sergey Dyasli 2019-08-29 12:11 ` Jan Beulich 2019-08-30 6:35 ` Chao Gao 2019-09-09 5:52 ` Chao Gao 2019-09-09 6:16 ` Jan Beulich 2019-08-29 12:22 ` Jan Beulich 2019-08-30 6:33 ` Chao Gao 2019-08-30 7:30 ` Jan Beulich 2019-08-22 7:51 ` [Xen-devel] [PATCH v9 00/15] improve late microcode loading Sergey Dyasli 2019-08-22 15:39 ` Chao Gao
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