netdev - Re: [PATCH v9 1/8] x86/vmware: Correct macro names

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Message-ID: <8356c1a0-4a4d-42e6-94dc-97abad2f8e04@broadcom.com>
Date: Thu, 25 Apr 2024 10:27:48 -0700
From: Alexey Makhalov <alexey.makhalov@...adcom.com>
To: Borislav Petkov <bp@...en8.de>
Cc: linux-kernel@...r.kernel.org, virtualization@...ts.linux.dev,
 hpa@...or.com, dave.hansen@...ux.intel.com, mingo@...hat.com,
 tglx@...utronix.de, x86@...nel.org, netdev@...r.kernel.org,
 richardcochran@...il.com, linux-input@...r.kernel.org,
 dmitry.torokhov@...il.com, zackr@...are.com,
 linux-graphics-maintainer@...are.com, pv-drivers@...are.com,
 timothym@...are.com, akaher@...are.com, dri-devel@...ts.freedesktop.org,
 daniel@...ll.ch, airlied@...il.com, tzimmermann@...e.de, mripard@...nel.org,
 maarten.lankhorst@...ux.intel.com, horms@...nel.org,
 kirill.shutemov@...ux.intel.com
Subject: Re: [PATCH v9 1/8] x86/vmware: Correct macro names



On 4/25/24 8:21 AM, Borislav Petkov wrote:
> On Wed, Apr 24, 2024 at 04:14:06PM -0700, Alexey Makhalov wrote:
>> VCPU_RESERVED and LEGACY_X2APIC are not VMware hypercall commands.
>> These are bits in return value of VMWARE_CMD_GETVCPU_INFO command.
>> Change VMWARE_CMD_ prefix to GETVCPU_INFO_ one. And move bit-shift
>> operation to the macro body.
> 
> I don't understand:
> 
> $ git grep GETVCPU_INFO
> arch/x86/kernel/cpu/vmware.c:51:#define VMWARE_CMD_GETVCPU_INFO  68
> arch/x86/kernel/cpu/vmware.c:478:       VMWARE_CMD(GETVCPU_INFO, eax, ebx, ecx, edx);
> 
> so that's a VMWARE_CMD 68, at least the prefix says so.
> 
> And those two are *bits* in that eax which that hypercall returns.
> 
> Or are those two bits generic but defined in a vmware-specific
> hypercall?
> 
> Hm.
> 

These are VMware hypercall commands:
#define VMWARE_CMD_GETVERSION    10
#define VMWARE_CMD_GETHZ         45
#define VMWARE_CMD_GETVCPU_INFO  68
#define VMWARE_CMD_STEALCLOCK    91


These are VMware-specific macros to analyze return values of 
corresponding commands. They are prefixed with command name.
#define GETVCPU_INFO_LEGACY_X2APIC           BIT(3)
#define GETVCPU_INFO_VCPU_RESERVED           BIT(31)

#define STEALCLOCK_NOT_AVAILABLE (-1)
#define STEALCLOCK_DISABLED        0
#define STEALCLOCK_ENABLED         1


Name VMWARE_CMD_LEGACY_X2APIC was not correct as LEGACY_X2APIC is not a 
command but the meaning of 3rd bit of a return value of 
VMWARE_CMD_GETVCPU_INFO. So, change it to GETVCPU_INFO_LEGACY_X2APIC.
The same change with GETVCPU_INFO_VCPU_RESERVED.
Both these bits are not generic.

--Alexey