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d="scan'208";a="14930062" From: Andrew Cooper To: Xen-devel Subject: [PATCH 09/11] x86/ucode/amd: Remove gratuitous memory allocations from cpu_request_microcode() Date: Tue, 31 Mar 2020 11:05:29 +0100 Message-ID: <20200331100531.4294-10-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20200331100531.4294-1-andrew.cooper3@citrix.com> References: <20200331100531.4294-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Andrew Cooper , Wei Liu , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Just as on the Intel side, there is no point having get_ucode_from_buffer_amd() make $N memory allocations and free $N-1 of them. Delete get_ucode_from_buffer_amd() and rewrite the loop in cpu_request_microcode() to have 'saved' point into 'buf' until we finally decide to duplicate that blob and return it to our caller. Introduce a new struct container_microcode to simplify interpreting the container format. Doubly indent the logic to substantially reduce the churn in a later change. Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Wei Liu CC: Roger Pau Monné --- xen/arch/x86/cpu/microcode/amd.c | 138 +++++++++++++-------------------------- 1 file changed, 47 insertions(+), 91 deletions(-) diff --git a/xen/arch/x86/cpu/microcode/amd.c b/xen/arch/x86/cpu/microcode/amd.c index 980e61c547..ae1276988f 100644 --- a/xen/arch/x86/cpu/microcode/amd.c +++ b/xen/arch/x86/cpu/microcode/amd.c @@ -70,6 +70,11 @@ struct mpbhdr { uint32_t len; uint8_t data[]; }; +struct container_microcode { + uint32_t type; /* UCODE_UCODE_TYPE */ + uint32_t len; + struct microcode_header_amd patch[]; +}; /* * Microcode updates for different CPUs are distinguished by their @@ -280,52 +285,6 @@ static int apply_microcode(const struct microcode_patch *patch) return 0; } -static int get_ucode_from_buffer_amd( - struct microcode_amd *mc_amd, - const void *buf, - size_t bufsize, - size_t *offset) -{ - const struct mpbhdr *mpbuf = buf + *offset; - - /* No more data */ - if ( *offset >= bufsize ) - { - printk(KERN_ERR "microcode: Microcode buffer overrun\n"); - return -EINVAL; - } - - if ( mpbuf->type != UCODE_UCODE_TYPE ) - { - printk(KERN_ERR "microcode: Wrong microcode payload type field\n"); - return -EINVAL; - } - - if ( (*offset + mpbuf->len) > bufsize ) - { - printk(KERN_ERR "microcode: Bad data in microcode data file\n"); - return -EINVAL; - } - - if ( !verify_patch_size(mpbuf->len) ) - { - printk(XENLOG_ERR "microcode: patch size mismatch\n"); - return -EINVAL; - } - - mc_amd->mpb = xmemdup_bytes(mpbuf->data, mpbuf->len); - if ( !mc_amd->mpb ) - return -ENOMEM; - - pr_debug("microcode: CPU%d size %zu, block size %u offset %zu equivID %#x rev %#x\n", - smp_processor_id(), bufsize, mpbuf->len, *offset, - mc_amd->mpb->processor_rev_id, mc_amd->mpb->patch_id); - - *offset += mpbuf->len + SECTION_HDR_SIZE; - - return 0; -} - static int scan_equiv_cpu_table( const void *data, size_t size_left, @@ -430,9 +389,9 @@ static int container_fast_forward(const void *data, size_t size_left, size_t *of static struct microcode_patch *cpu_request_microcode(const void *buf, size_t size) { struct microcode_amd *mc_amd; - struct microcode_header_amd *saved = NULL; + const 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 cpu = smp_processor_id(); const struct cpu_signature *sig = &per_cpu(cpu_sig, cpu); @@ -497,57 +456,54 @@ static struct microcode_patch *cpu_request_microcode(const void *buf, size_t siz * It's possible the data file has multiple matching ucode, * lets keep searching till the latest version */ - while ( (error = get_ucode_from_buffer_amd(mc_amd, buf, size, - &offset)) == 0 ) + buf += offset; + size -= offset; { - /* - * If the new ucode covers current CPU, compare ucodes and store the - * one with higher revision. - */ - if ( (microcode_fits(mc_amd->mpb) != MIS_UCODE) && - (!saved || (compare_header(mc_amd->mpb, saved) == NEW_UCODE)) ) + while ( size ) { - xfree(saved); - saved = mc_amd->mpb; - } - else - { - xfree(mc_amd->mpb); - mc_amd->mpb = NULL; - } + const struct container_microcode *mc; + + if ( size < sizeof(*mc) || + (mc = buf)->type != UCODE_UCODE_TYPE || + size - sizeof(*mc) < mc->len || + !verify_patch_size(mc->len) ) + { + printk(XENLOG_ERR "microcode: Bad microcode data\n"); + error = -EINVAL; + break; + } - if ( offset >= size ) - break; + /* + * If the new ucode covers current CPU, compare ucodes and store the + * one with higher revision. + */ + if ( (microcode_fits(mc->patch) != MIS_UCODE) && + (!saved || (compare_header(mc->patch, saved) == NEW_UCODE)) ) + { + saved = mc->patch; + saved_size = mc->len; + } - /* - * 1. Given a situation where multiple containers exist and correct - * patch lives on a container that is not the last container. - * 2. We match equivalent ids using find_equiv_cpu_id() from the - * earlier while() (On this case, matches on earlier container - * file and we break) - * 3. Proceed to while ( (error = get_ucode_from_buffer_amd(mc_amd, - * buf, size, &offset)) == 0 ) - * 4. Find correct patch using microcode_fits() and apply the patch - * (Assume: apply_microcode() is successful) - * 5. The while() loop from (3) continues to parse the binary as - * there is a subsequent container file, but... - * 6. ...a correct patch can only be on one container and not on any - * subsequent ones. (Refer docs for more info) Therefore, we - * don't have to parse a subsequent container. So, we can abort - * the process here. - * 7. This ensures that we retain a success value (= 0) to 'error' - * before if ( mpbuf->type != UCODE_UCODE_TYPE ) evaluates to - * false and returns -EINVAL. - */ - if ( offset + SECTION_HDR_SIZE <= size && - *(const uint32_t *)(buf + offset) == UCODE_MAGIC ) - break; + /* Move over the microcode blob. */ + buf += sizeof(*mc) + mc->len; + size -= sizeof(*mc) + mc->len; + + /* + * Peek ahead. If we see the start of another container, we've + * exhaused all microcode blobs in this container. Exit cleanly. + */ + if ( size >= 4 && *(const uint32_t *)buf == UCODE_MAGIC ) + break; + } } if ( saved ) { - mc_amd->mpb = saved; - patch = mc_amd; + mc_amd->mpb = xmemdup_bytes(saved, saved_size); + if ( mc_amd->mpb ) + patch = mc_amd; + else + error = -ENOMEM; } else free_patch(mc_amd); -- 2.11.0