Xen-Devel Archive on lore.kernel.org
 help / color / Atom feed
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: Fri, 23 Aug 2019 10:11:21 +0200
Message-ID: <20190823081121.khm5622trozzhswe@Air-de-Roger> (raw)
In-Reply-To: <1566177928-19114-13-git-send-email-chao.gao@intel.com>

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.

> 
> Signed-off-by: Chao Gao <chao.gao@intel.com>
> ---
> Changes in v9:
>  - new
> ---
>  xen/arch/x86/microcode_amd.c   | 99 +++++++++++++++---------------------------
>  xen/arch/x86/microcode_intel.c | 65 ++++++++++-----------------
>  2 files changed, 58 insertions(+), 106 deletions(-)
> 
> diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c
> index 6353323..ec1c2eb 100644
> --- a/xen/arch/x86/microcode_amd.c
> +++ b/xen/arch/x86/microcode_amd.c
> @@ -194,36 +194,6 @@ static bool match_cpu(const struct microcode_patch *patch)
>      return patch && (microcode_fits(patch->mc_amd) == NEW_UCODE);
>  }
>  
> -static struct microcode_patch *alloc_microcode_patch(
> -    const struct microcode_amd *mc_amd)
> -{
> -    struct microcode_patch *microcode_patch = xmalloc(struct microcode_patch);
> -    struct microcode_amd *cache = xmalloc(struct microcode_amd);
> -    void *mpb = xmalloc_bytes(mc_amd->mpb_size);
> -    struct equiv_cpu_entry *equiv_cpu_table =
> -                                xmalloc_bytes(mc_amd->equiv_cpu_table_size);
> -
> -    if ( !microcode_patch || !cache || !mpb || !equiv_cpu_table )
> -    {
> -        xfree(microcode_patch);
> -        xfree(cache);
> -        xfree(mpb);
> -        xfree(equiv_cpu_table);
> -        return ERR_PTR(-ENOMEM);
> -    }
> -
> -    memcpy(mpb, mc_amd->mpb, mc_amd->mpb_size);
> -    cache->mpb = mpb;
> -    cache->mpb_size = mc_amd->mpb_size;
> -    memcpy(equiv_cpu_table, mc_amd->equiv_cpu_table,
> -           mc_amd->equiv_cpu_table_size);
> -    cache->equiv_cpu_table = equiv_cpu_table;
> -    cache->equiv_cpu_table_size = mc_amd->equiv_cpu_table_size;
> -    microcode_patch->mc_amd = cache;
> -
> -    return microcode_patch;
> -}
> -
>  static void free_patch(void *mc)
>  {
>      struct microcode_amd *mc_amd = mc;
> @@ -320,18 +290,10 @@ static int get_ucode_from_buffer_amd(
>          return -EINVAL;
>      }
>  
> -    if ( mc_amd->mpb_size < mpbuf->len )
> -    {
> -        if ( mc_amd->mpb )
> -        {
> -            xfree(mc_amd->mpb);
> -            mc_amd->mpb_size = 0;
> -        }
> -        mc_amd->mpb = xmalloc_bytes(mpbuf->len);
> -        if ( mc_amd->mpb == NULL )
> -            return -ENOMEM;
> -        mc_amd->mpb_size = mpbuf->len;
> -    }
> +    mc_amd->mpb = xmalloc_bytes(mpbuf->len);
> +    if ( mc_amd->mpb == NULL )

Nit:

if ( !mc_amd->mpb )

is the usual idiom used in Xen.

> +        return -ENOMEM;
> +    mc_amd->mpb_size = mpbuf->len;
>      memcpy(mc_amd->mpb, mpbuf->data, mpbuf->len);
>  
>      pr_debug("microcode: CPU%d size %zu, block size %u offset %zu equivID %#x rev %#x\n",
> @@ -451,8 +413,9 @@ static struct microcode_patch *cpu_request_microcode(const void *buf,
>                                                       size_t bufsize)
>  {
>      struct microcode_amd *mc_amd;
> +    struct microcode_header_amd *saved = NULL;
>      struct microcode_patch *patch = NULL;
> -    size_t offset = 0;
> +    size_t offset = 0, saved_size = 0;
>      int error = 0;
>      unsigned int current_cpu_id;
>      unsigned int equiv_cpu_id;
> @@ -542,29 +505,21 @@ static struct microcode_patch *cpu_request_microcode(const void *buf,
>      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);
>  
>          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?

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?

ie: in the Intel counterpart below you don't seem to free the mc
cursor used for the get_next_ucode_from_buffer loop.

> +        free_patch(mc_amd);
> +    }
>  
>    out:
>      if ( error && !patch )
> diff --git a/xen/arch/x86/microcode_intel.c b/xen/arch/x86/microcode_intel.c
> index 96b38f8..ae5759f 100644
> --- a/xen/arch/x86/microcode_intel.c
> +++ b/xen/arch/x86/microcode_intel.c
> @@ -282,25 +282,6 @@ static enum microcode_match_result compare_patch(
>                                                                  OLD_UCODE;
>  }
>  
> -static struct microcode_patch *alloc_microcode_patch(
> -    const struct microcode_header_intel *mc_header)
> -{
> -    unsigned long total_size = get_totalsize(mc_header);
> -    void *new_mc = xmalloc_bytes(total_size);
> -    struct microcode_patch *new_patch = xmalloc(struct microcode_patch);
> -
> -    if ( !new_patch || !new_mc )
> -    {
> -        xfree(new_patch);
> -        xfree(new_mc);
> -        return ERR_PTR(-ENOMEM);
> -    }
> -    memcpy(new_mc, mc_header, total_size);
> -    new_patch->mc_intel = new_mc;
> -
> -    return new_patch;
> -}
> -
>  static int apply_microcode(const struct microcode_patch *patch)
>  {
>      unsigned long flags;
> @@ -379,47 +360,47 @@ static struct microcode_patch *cpu_request_microcode(const void *buf,
>  {
>      long offset = 0;
>      int error = 0;
> -    void *mc;
> +    struct microcode_intel *mc, *saved = NULL;
>      struct microcode_patch *patch = NULL;
>  
> -    while ( (offset = get_next_ucode_from_buffer(&mc, buf, size, offset)) > 0 )
> +    while ( (offset = get_next_ucode_from_buffer((void **)&mc, buf,
> +                                                 size, offset)) > 0 )
>      {
> -        struct microcode_patch *new_patch;
> -
>          error = microcode_sanity_check(mc);
>          if ( error )
> -            break;
> -
> -        new_patch = alloc_microcode_patch(mc);
> -        if ( IS_ERR(new_patch) )
>          {
> -            error = PTR_ERR(new_patch);
> +            xfree(mc);
>              break;
>          }
>  
>          /*
> -         * If the new patch covers current CPU, compare patches and store the
> +         * If the new update covers current CPU, compare updates and store the
>           * one with higher revision.
>           */
> -        if ( (microcode_update_match(&new_patch->mc_intel->hdr) != MIS_UCODE) &&
> -             (!patch || (compare_patch(new_patch, patch) == NEW_UCODE)) )
> +        if ( (microcode_update_match(&mc->hdr) != MIS_UCODE) &&
> +             (!saved || (mc->hdr.rev > saved->hdr.rev)) )
>          {
> -            struct microcode_patch *tmp = patch;
> -
> -            patch = new_patch;
> -            new_patch = tmp;
> +            xfree(saved);
> +            saved = mc;
>          }
> -
> -        if ( new_patch )
> -            microcode_free_patch(new_patch);
> -
> -        xfree(mc);
> +        else
> +            xfree(mc);
>      }
> -    if ( offset > 0 )
> -        xfree(mc);
>      if ( offset < 0 )
>          error = offset;
>  
> +    if ( saved )
> +    {
> +        patch = xmalloc(struct microcode_patch);
> +        if ( patch )
> +            patch->mc_intel = saved;
> +        else
> +        {
> +            xfree(saved);
> +            error = -ENOMEM;
> +        }
> +    }
> +

The above code looks suspiciously similar to the AMD
cpu_request_microcode counterpart, which makes me think it could be
further abstracted in order to reduce this duplication. In any case,
this can be done in a follow up patch.

Thanks, Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  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 [this message]
2019-08-26  7:03     ` Chao Gao
2019-08-26  8:11       ` Roger Pau Monné
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

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190823081121.khm5622trozzhswe@Air-de-Roger \
    --to=roger.pau@citrix.com \
    --cc=andrew.cooper3@citrix.com \
    --cc=ashok.raj@intel.com \
    --cc=chao.gao@intel.com \
    --cc=jbeulich@suse.com \
    --cc=wl@xen.org \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Xen-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/xen-devel/0 xen-devel/git/0.git
	git clone --mirror https://lore.kernel.org/xen-devel/1 xen-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 xen-devel xen-devel/ https://lore.kernel.org/xen-devel \
		xen-devel@lists.xenproject.org xen-devel@lists.xen.org xen-devel@archiver.kernel.org
	public-inbox-index xen-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.xenproject.lists.xen-devel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox