linux-kernel - Re: [PATCH v3 04/16] platform/x86/intel/ifs: Remove memory allocation from load path

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Date:   Thu, 17 Nov 2022 09:51:30 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Jithu Joseph <jithu.joseph@...el.com>, markgross@...nel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        gregkh@...uxfoundation.org, ashok.raj@...el.com,
        tony.luck@...el.com, linux-kernel@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, patches@...ts.linux.dev,
        ravi.v.shankar@...el.com, thiago.macieira@...el.com,
        athenas.jimenez.gonzalez@...el.com, sohil.mehta@...el.com
Subject: Re: [PATCH v3 04/16] platform/x86/intel/ifs: Remove memory allocation
 from load path

Hi,

On 11/17/22 04:59, Jithu Joseph wrote:
> IFS requires tests to be authenticated once for each CPU socket
> on a system.
> 
> scan_chunks_sanity_check() was dynamically allocating memory
> to store the state of whether tests have been authenticated on
> each socket for every load operation.
> 
> Move the memory allocation to init path.
> 
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Suggested-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
> ---
>  drivers/platform/x86/intel/ifs/ifs.h  |  2 ++
>  drivers/platform/x86/intel/ifs/core.c | 13 +++++++++++--
>  drivers/platform/x86/intel/ifs/load.c | 14 ++++----------
>  3 files changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
> index 3ff1d9aaeaa9..3a051890d9e7 100644
> --- a/drivers/platform/x86/intel/ifs/ifs.h
> +++ b/drivers/platform/x86/intel/ifs/ifs.h
> @@ -229,4 +229,6 @@ void ifs_load_firmware(struct device *dev);
>  int do_core_test(int cpu, struct device *dev);
>  const struct attribute_group **ifs_get_groups(void);
>  
> +extern bool *ifs_pkg_auth;
> +

This is not necessary and ugly, nack for this patch as-is (sorry).

You can simply add this pointer to "struct ifs_data" and then
alloc it in ifs_init() before the misc_register call.

scan_chunks_sanity_check() already has a "struct ifs_data *ifsd",
so it can easily access ifs_pkg_auth through that when you make
ifs_pkg_auth part of "struct ifs_data".

Regards,

Hans
\


>  #endif
> diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
> index 5fb7f655c291..4b39f2359180 100644
> --- a/drivers/platform/x86/intel/ifs/core.c
> +++ b/drivers/platform/x86/intel/ifs/core.c
> @@ -4,6 +4,7 @@
>  #include <linux/module.h>
>  #include <linux/kdev_t.h>
>  #include <linux/semaphore.h>
> +#include <linux/slab.h>
>  
>  #include <asm/cpu_device_id.h>
>  
> @@ -30,6 +31,8 @@ static struct ifs_device ifs_device = {
>  	},
>  };
>  
> +bool *ifs_pkg_auth;
> +
>  static int __init ifs_init(void)
>  {
>  	const struct x86_cpu_id *m;
> @@ -51,8 +54,13 @@ static int __init ifs_init(void)
>  	ifs_device.misc.groups = ifs_get_groups();
>  
>  	if ((msrval & BIT(ifs_device.data.integrity_cap_bit)) &&
> -	    !misc_register(&ifs_device.misc))
> -		return 0;
> +	    !misc_register(&ifs_device.misc)) {
> +		ifs_pkg_auth = kmalloc_array(topology_max_packages(), sizeof(bool), GFP_KERNEL);
> +		if (!ifs_pkg_auth)
> +			return -ENOMEM;
> +		else
> +			return 0;
> +	}
>  
>  	return -ENODEV;
>  }
> @@ -60,6 +68,7 @@ static int __init ifs_init(void)
>  static void __exit ifs_exit(void)
>  {
>  	misc_deregister(&ifs_device.misc);
> +	kfree(ifs_pkg_auth);
>  }
>  
>  module_init(ifs_init);
> diff --git a/drivers/platform/x86/intel/ifs/load.c b/drivers/platform/x86/intel/ifs/load.c
> index 89ce265887ea..c914e4d359db 100644
> --- a/drivers/platform/x86/intel/ifs/load.c
> +++ b/drivers/platform/x86/intel/ifs/load.c
> @@ -3,7 +3,6 @@
>  
>  #include <linux/firmware.h>
>  #include <asm/cpu.h>
> -#include <linux/slab.h>
>  #include <asm/microcode_intel.h>
>  
>  #include "ifs.h"
> @@ -118,16 +117,12 @@ static void copy_hashes_authenticate_chunks(struct work_struct *work)
>   */
>  static int scan_chunks_sanity_check(struct device *dev)
>  {
> -	int metadata_size, curr_pkg, cpu, ret = -ENOMEM;
> +	int metadata_size, curr_pkg, cpu, ret;
>  	struct ifs_data *ifsd = ifs_get_data(dev);
> -	bool *package_authenticated;
>  	struct ifs_work local_work;
>  	char *test_ptr;
>  
> -	package_authenticated = kcalloc(topology_max_packages(), sizeof(bool), GFP_KERNEL);
> -	if (!package_authenticated)
> -		return ret;
> -
> +	memset(ifs_pkg_auth, 0, (topology_max_packages() * sizeof(bool)));
>  	metadata_size = ifs_header_ptr->metadata_size;
>  
>  	/* Spec says that if the Meta Data Size = 0 then it should be treated as 2000 */
> @@ -150,7 +145,7 @@ static int scan_chunks_sanity_check(struct device *dev)
>  	cpus_read_lock();
>  	for_each_online_cpu(cpu) {
>  		curr_pkg = topology_physical_package_id(cpu);
> -		if (package_authenticated[curr_pkg])
> +		if (ifs_pkg_auth[curr_pkg])
>  			continue;
>  		reinit_completion(&ifs_done);
>  		local_work.dev = dev;
> @@ -161,12 +156,11 @@ static int scan_chunks_sanity_check(struct device *dev)
>  			ret = -EIO;
>  			goto out;
>  		}
> -		package_authenticated[curr_pkg] = 1;
> +		ifs_pkg_auth[curr_pkg] = 1;
>  	}
>  	ret = 0;
>  out:
>  	cpus_read_unlock();
> -	kfree(package_authenticated);
>  
>  	return ret;
>  }