Re: [PATCH v7 022/102] KVM: TDX: create/destroy VM structure

Isaku Yamahata
2022-07-12T06:21:07Z

On Thu, Jul 07, 2022 at 02:16:29PM +0800,
Yuan Yao <yuan.yao@linux.intel.com> wrote:

> On Mon, Jun 27, 2022 at 02:53:14PM -0700, isaku.yamahata@intel.com wrote:
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index 3675f7de2735..63f3c7a02cc8 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
...
> > int __init tdx_module_setup(void)
> > {
> > const struct tdsysinfo_struct *tdsysinfo;
> > @@ -48,6 +406,8 @@ int __init tdx_module_setup(void)
> > return ret;
> > }
> >
> > + tdx_global_keyid = tdx_get_global_keyid();
>
> I remember there's another static variable also named
> "tdx_global_keyid" in arch/x86/virt/vmx/tdx/tdx.c ?
> We can just use tdx_get_global_keyid() here without introducing
> another static variable.

Hmm, it can be done by exporting the variable itself.

static inline int tdx_keyid_alloc(void) { return -EOPNOTSUPP; }
static inline void tdx_keyid_free(int keyid) { }
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index c1d41350e021..71f6d026bfd2 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -43,14 +43,6 @@ struct tdx_capabilities {
struct tdx_cpuid_config cpuid_configs[TDX_MAX_NR_CPUID_CONFIGS];
};

-/*
- * Key id globally used by TDX module: TDX module maps TDR with this TDX global
- * key id. TDR includes key id assigned to the TD. Then TDX module maps other
- * TD-related pages with the assigned key id. TDR requires this TDX global key
- * id for cache flush unlike other TD-related pages.
- */
-static u32 tdx_global_keyid __read_mostly;
-
/* Capabilities of KVM + the TDX module. */
static struct tdx_capabilities tdx_caps;

@@ -3572,8 +3564,6 @@ int __init tdx_module_setup(void)
return ret;
}

- tdx_global_keyid = tdx_get_global_keyid();
-
tdsysinfo = tdx_get_sysinfo();
if (tdsysinfo->num_cpuid_config > TDX_MAX_NR_CPUID_CONFIGS)
return -EIO;
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index ea35230f0814..68ddcb06c7f1 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -65,13 +65,8 @@ static struct cmr_info tdx_cmr_array[MAX_CMRS] __aligned(CMR_INFO_ARRAY_ALIGNMEN
static int tdx_cmr_num;

/* TDX module global KeyID. Used in TDH.SYS.CONFIG ABI. */
-static u32 __read_mostly tdx_global_keyid;
-
-u32 tdx_get_global_keyid(void)
-{
- return tdx_global_keyid;
-}
-EXPORT_SYMBOL_GPL(tdx_get_global_keyid);
+u32 tdx_global_keyid __ro_after_init;
+EXPORT_SYMBOL_GPL(tdx_global_keyid);

u32 tdx_get_num_keyid(void)
{

--
Isaku Yamahata <isaku.yamahata@gmail.com>