From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Wei Liu" <wl@xen.org>, "Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH 5/7] x86/ucode/intel: Clean up microcode_update_match()
Date: Mon, 23 Mar 2020 10:17:22 +0000 [thread overview]
Message-ID: <20200323101724.15655-6-andrew.cooper3@citrix.com> (raw)
In-Reply-To: <20200323101724.15655-1-andrew.cooper3@citrix.com>
Implement a new get_ext_sigtable() helper to abstract the logic for
identifying whether an extended signature table exists. As part of this,
rename microcode_intel.bits to data and change its type so it can be usefully
used in combination with the datasize header field.
Also, replace the sigmatch() macro with a static inline with a more useful
API, and an explanation of why it is safe to drop one of the previous
conditionals.
No practical change in behaviour.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wl@xen.org>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
xen/arch/x86/cpu/microcode/intel.c | 75 +++++++++++++++++++++++++-------------
1 file changed, 49 insertions(+), 26 deletions(-)
diff --git a/xen/arch/x86/cpu/microcode/intel.c b/xen/arch/x86/cpu/microcode/intel.c
index dfe44679be..bc3bbf139e 100644
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -61,7 +61,7 @@ struct microcode_header_intel {
struct microcode_intel {
struct microcode_header_intel hdr;
- unsigned int bits[0];
+ uint8_t data[];
};
/* microcode format is extended from prescott processors */
@@ -98,8 +98,41 @@ static uint32_t get_totalsize(const struct microcode_header_intel *hdr)
return hdr->_totalsize ?: PPRO_UCODE_DATASIZE + MC_HEADER_SIZE;
}
-#define sigmatch(s1, s2, p1, p2) \
- (((s1) == (s2)) && (((p1) & (p2)) || (((p1) == 0) && ((p2) == 0))))
+/*
+ * A piece of microcode has an extended signature table if there is space
+ * between the end of data[] and the total size. (This logic also works
+ * appropriately for Pentium Pro/II microcode, which has 0 for both size
+ * fields, and no extended signature table.)
+ */
+static const struct extended_sigtable *get_ext_sigtable(
+ const struct microcode_intel *mc)
+{
+ if ( mc->hdr._totalsize > (MC_HEADER_SIZE + mc->hdr._datasize) )
+ return (void *)&mc->data[mc->hdr._datasize];
+
+ return NULL;
+}
+
+/*
+ * A piece of microcode is applicable for a CPU if:
+ * 1) the signatures (CPUID.1.EAX - Family/Model/Stepping) match, and
+ * 2) The Platform Flags bitmap intersect.
+ *
+ * A CPU will have a single Platform Flag bit, while the microcode may be
+ * common to multiple platforms and have multiple bits set.
+ *
+ * Note: The Pentium Pro/II microcode didn't use platform flags, and should
+ * treat 0 as a match. However, Xen being 64bit means that the cpu signature
+ * won't match, allowing us to simplify the logic.
+ */
+static bool signature_maches(const struct cpu_signature *cpu_sig,
+ unsigned int ucode_sig, unsigned int ucode_pf)
+{
+ if ( cpu_sig->sig != ucode_sig )
+ return false;
+
+ return cpu_sig->pf & ucode_pf;
+}
#define exttable_size(et) ((et)->count * EXT_SIGNATURE_SIZE + EXT_HEADER_SIZE)
@@ -221,36 +254,26 @@ static int microcode_sanity_check(const struct microcode_intel *mc)
static enum microcode_match_result microcode_update_match(
const struct microcode_intel *mc)
{
- const struct microcode_header_intel *mc_header = &mc->hdr;
- const struct extended_sigtable *ext_header;
- const struct extended_signature *ext_sig;
+ const struct extended_sigtable *ext;
unsigned int i;
struct cpu_signature *cpu_sig = &this_cpu(cpu_sig);
- unsigned int sig = cpu_sig->sig;
- unsigned int pf = cpu_sig->pf;
- unsigned int rev = cpu_sig->rev;
- unsigned long data_size = get_datasize(mc_header);
- const void *end = (const void *)mc_header + get_totalsize(mc_header);
ASSERT(!microcode_sanity_check(mc));
- if ( sigmatch(sig, mc_header->sig, pf, mc_header->pf) )
- return (mc_header->rev > rev) ? NEW_UCODE : OLD_UCODE;
- ext_header = (const void *)(mc_header + 1) + data_size;
- ext_sig = (const void *)(ext_header + 1);
+ /* Check the main microcode signature. */
+ if ( signature_maches(cpu_sig, mc->hdr.sig, mc->hdr.pf) )
+ goto found;
- /*
- * Make sure there is enough space to hold an extended header and enough
- * array elements.
- */
- if ( end <= (const void *)ext_sig )
- return MIS_UCODE;
-
- for ( i = 0; i < ext_header->count; i++ )
- if ( sigmatch(sig, ext_sig[i].sig, pf, ext_sig[i].pf) )
- return (mc_header->rev > rev) ? NEW_UCODE : OLD_UCODE;
+ /* If there is an extended signature table, check each of them. */
+ if ( (ext = get_ext_sigtable(mc)) != NULL )
+ for ( i = 0; i < ext->count; ++i )
+ if ( signature_maches(cpu_sig, ext->sigs[i].sig, ext->sigs[i].pf) )
+ goto found;
return MIS_UCODE;
+
+ found:
+ return mc->hdr.rev > cpu_sig->rev ? NEW_UCODE : OLD_UCODE;
}
static bool match_cpu(const struct microcode_patch *patch)
@@ -303,7 +326,7 @@ static int apply_microcode(const struct microcode_patch *patch)
BUG_ON(local_irq_is_enabled());
/* write microcode via MSR 0x79 */
- wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc_intel->bits);
+ wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc_intel->data);
wrmsrl(MSR_IA32_UCODE_REV, 0x0ULL);
/* As documented in the SDM: Do a CPUID 1 here */
--
2.11.0
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next prev parent reply other threads:[~2020-03-23 10:18 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 10:17 [Xen-devel] [PATCH 0/7] x86/ucode: Cleanup and fixes - Part 3/n (Intel) Andrew Cooper
2020-03-23 10:17 ` [Xen-devel] [PATCH 1/7] x86/ucode: Document the behaviour of the microcode_ops hooks Andrew Cooper
2020-03-23 12:33 ` Jan Beulich
2020-03-23 13:26 ` Andrew Cooper
2020-03-23 14:24 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 2/7] x86/ucode/intel: Adjust microcode_sanity_check() to not take void * Andrew Cooper
2020-03-25 13:23 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 3/7] x86/ucode/intel: Remove gratuitous memory allocations from cpu_request_microcode() Andrew Cooper
2020-03-25 13:34 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 4/7] x86/ucode/intel: Reimplement get_{data, total}size() helpers Andrew Cooper
2020-03-25 13:41 ` Jan Beulich
2020-03-26 14:35 ` Andrew Cooper
2020-03-26 14:56 ` Jan Beulich
2020-03-26 15:09 ` Andrew Cooper
2020-03-26 15:19 ` Jan Beulich
2020-03-23 10:17 ` Andrew Cooper [this message]
2020-03-25 13:51 ` [Xen-devel] [PATCH 5/7] x86/ucode/intel: Clean up microcode_update_match() Jan Beulich
2020-03-26 14:36 ` Andrew Cooper
2020-03-23 10:17 ` [Xen-devel] [PATCH 6/7] x86/ucode/intel: Clean up microcode_sanity_check() Andrew Cooper
2020-03-25 14:07 ` Jan Beulich
2020-03-26 14:41 ` Andrew Cooper
2020-03-26 15:02 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 7/7] x86/ucode/intel: Fold structures together Andrew Cooper
2020-03-25 14:16 ` Jan Beulich
2020-03-25 14:32 ` Andrew Cooper
2020-03-26 12:24 ` Jan Beulich
2020-03-26 14:50 ` Andrew Cooper
2020-03-26 15:05 ` Jan Beulich
2020-03-27 12:40 ` Andrew Cooper
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