Re: [PATCH v2 1/4] x86/vmware: Update platform detection code for VMCALL/VMMCALL hypercalls

[VMware]

Thanks for reviewing, Borislav. Comments inline.

On 8/27/19 2:56 PM, Borislav Petkov wrote:
On Fri, Aug 23, 2019 at 10:13:13AM +0200, Thomas Hellström (VMware) wrote:

+
+#define VMWARE_CMD(cmd, eax, ebx, ecx, edx) do {               \
+       switch (vmware_hypercall_mode) {                        \
+       case CPUID_VMWARE_FEATURES_ECX_VMCALL:                  \
+               VMWARE_VMCALL(cmd, eax, ebx, ecx, edx);         \
+               break;                                          \
+       case CPUID_VMWARE_FEATURES_ECX_VMMCALL:                 \
+               VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx);        \
+               break;                                          \
+       default:                                                \
Please integrate scripts/checkpatch.pl into your patch creation
workflow. Some of the warnings/errors *actually* make sense:

WARNING: Possible switch case/default not preceded by break or fallthrough 
comment
#110: FILE: arch/x86/kernel/cpu/vmware.c:81:
+       case CPUID_VMWARE_FEATURES_ECX_VMMCALL:                 \

WARNING: Possible switch case/default not preceded by break or fallthrough 
comment
#113: FILE: arch/x86/kernel/cpu/vmware.c:84:
+       default:

In this case, we're going to enable -Wimplicit-fallthrough by default at
some point.

We *do* have checkpatch.pl in the workflow. In this case I figured the 
warnings actually didn't make sense. There are breaks present and 
-Wimplicit-fallthrough doesn't complain...


        (unsigned int) vmware_hypercall_mode);

Is that supposed to be debug output? If so, pr_dbg().

This is intentionally intended to be part of the initial output.


+
                        return CPUID_VMWARE_INFO_LEAF;
+               }
        } else if (dmi_available && dmi_name_in_serial("VMware") &&
                   __vmware_platform())
What sets vmware_hypercall_mode in this case? Or is the 0 magic to mean,
use the default: VMWARE_PORT inl call?

Yes, Perhaps I should add a comment about that.


Also, you could restructure that function something like this to save yourself
an indentation level or two and make it more easily readable:

static uint32_t __init vmware_platform(void)
{
         unsigned int hyper_vendor_id[3];
         unsigned int eax;

         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
                 if (dmi_available && dmi_name_in_serial("VMware") && 
__vmware_platform())
                         return 1;
         }

         cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
               &hyper_vendor_id[1], &hyper_vendor_id[2]);

         if (!memcmp(hyper_vendor_id, "VMwareVMware", 12)) {
                 if (eax >= CPUID_VMWARE_FEATURES_LEAF)
                         vmware_hypercall_mode = vmware_select_hypercall();

                 pr_info("hypercall mode: 0x%02x\n", (unsigned int) 
vmware_hypercall_mode);

                 return CPUID_VMWARE_INFO_LEAF;
         }
         return 0;
}

Sure, I'll add that as a separate patch.

For the other comments, I'll fix up and respin.

Thanks,

Thomas