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Subject[tip:x86/microcode] x86/microcode/AMD: Simplify patch family detection
Commit-ID:  6cdce951f7a1d8161910d5cd9bd9e6197bf5cc97
Gitweb: https://git.kernel.org/tip/6cdce951f7a1d8161910d5cd9bd9e6197bf5cc97
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Thu, 19 Jul 2018 15:47:07 +0200
Committer: Borislav Petkov <bp@suse.de>
CommitDate: Mon, 19 Nov 2018 10:51:05 +0100

x86/microcode/AMD: Simplify patch family detection

Instead of traversing the equivalence table, compute the family a patch
is for, from the processor revision ID in the microcode header.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: x86@kernel.org
Link: https://lkml.kernel.org/r/20181107170218.7596-8-bp@alien8.de
---
arch/x86/kernel/cpu/microcode/amd.c | 27 +++------------------------
1 file changed, 3 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 8f012a7f88c4..b4450374f4b1 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -540,20 +540,6 @@ static u16 __find_equiv_id(unsigned int cpu)
return find_equiv_id(equiv_cpu_table, uci->cpu_sig.sig);
}

-static u32 find_cpu_family_by_equiv_cpu(u16 equiv_cpu)
-{
- int i = 0;
-
- BUG_ON(!equiv_cpu_table);
-
- while (equiv_cpu_table[i].equiv_cpu != 0) {
- if (equiv_cpu == equiv_cpu_table[i].equiv_cpu)
- return equiv_cpu_table[i].installed_cpu;
- i++;
- }
- return 0;
-}
-
/*
* a small, trivial cache of per-family ucode patches
*/
@@ -732,7 +718,7 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover)
struct microcode_header_amd *mc_hdr;
unsigned int patch_size, crnt_size;
struct ucode_patch *patch;
- u32 proc_fam;
+ u8 patch_fam;
u16 proc_id;

patch_size = verify_patch(family, fw, leftover, false);
@@ -746,15 +732,8 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover)
mc_hdr = (struct microcode_header_amd *)(fw + SECTION_HDR_SIZE);
proc_id = mc_hdr->processor_rev_id;

- proc_fam = find_cpu_family_by_equiv_cpu(proc_id);
- if (!proc_fam) {
- pr_err("No patch family for equiv ID: 0x%04x\n", proc_id);
- return crnt_size;
- }
-
- /* check if patch is for the current family */
- proc_fam = ((proc_fam >> 8) & 0xf) + ((proc_fam >> 20) & 0xff);
- if (proc_fam != family)
+ patch_fam = 0xf + (proc_id >> 12);
+ if (patch_fam != family)
return crnt_size;

if (mc_hdr->nb_dev_id || mc_hdr->sb_dev_id) {
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