linux-kernel - [PATCH 02/13] x86/microcode: Do not load from filesystem for CPU hot add

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Message-Id: <20221014200913.14644-3-ashok.raj@intel.com>
Date:   Fri, 14 Oct 2022 13:09:02 -0700
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        LKML Mailing List <linux-kernel@...r.kernel.org>,
        X86-kernel <x86@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Arjan van de Ven <arjan.van.de.ven@...el.com>,
        Jacob Jun Pan <jacob.jun.pan@...el.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: [PATCH 02/13] x86/microcode: Do not load from filesystem for CPU hot add

When request_microcode_fw() is called, refresh_fw parameter must be set
only when late loading. Currently during CPU hotplug, the path is as
follows.

mc_device_add() -> microcode_init_cpu() ->
				request_microcode_fw(refresh_hw=true)

Consider if a new microcode file was just copied, but have not yet
performed a late load. Now adding a new CPU will result in loading that
microcode file vs the rest of the CPUs in the system would have a previous
revision of what was loaded earlier.

Moreover this doesn't need to be any different from logical cpu online
flow, microcode_update_cpu() and mc_device_add() seem to be doing the
opposite things.

Seems like there is no good use for the refresh_fw parameter in
microcode_init_cpu(), so simply drop it.

Signed-off-by: Ashok Raj <ashok.raj@...el.com>
---
 arch/x86/kernel/cpu/microcode/core.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 6a41cee242f6..e4135b4fdbc6 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -599,7 +599,7 @@ static enum ucode_state microcode_resume_cpu(int cpu)
 	return UCODE_OK;
 }
 
-static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
+static enum ucode_state microcode_init_cpu(int cpu)
 {
 	enum ucode_state ustate;
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
@@ -614,7 +614,8 @@ static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
 	if (system_state != SYSTEM_RUNNING)
 		return UCODE_NFOUND;
 
-	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, refresh_fw);
+	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev,
+						     false);
 	if (ustate == UCODE_NEW) {
 		pr_debug("CPU%d updated upon init\n", cpu);
 		apply_microcode_on_target(cpu);
@@ -633,7 +634,7 @@ static enum ucode_state microcode_update_cpu(int cpu)
 	if (uci->valid)
 		return microcode_resume_cpu(cpu);
 
-	return microcode_init_cpu(cpu, false);
+	return microcode_init_cpu(cpu);
 }
 
 static int mc_device_add(struct device *dev, struct subsys_interface *sif)
@@ -649,7 +650,7 @@ static int mc_device_add(struct device *dev, struct subsys_interface *sif)
 	if (err)
 		return err;
 
-	if (microcode_init_cpu(cpu, true) == UCODE_ERROR)
+	if (microcode_init_cpu(cpu) == UCODE_ERROR)
 		return -EINVAL;
 
 	return err;
-- 
2.34.1