On 4/1/21 2:19 PM, Dave Hansen wrote:
On 4/1/21 2:15 PM, Kuppuswamy, Sathyanarayanan wrote:
On 4/1/21 2:08 PM, Dave Hansen wrote:
On 2/5/21 3:38 PM, Kuppuswamy Sathyanarayanan wrote:
+bool is_tdx_guest(void)
+{
+ return static_cpu_has(X86_FEATURE_TDX_GUEST);
+}
Why do you need is_tdx_guest() as opposed to calling
cpu_feature_enabled(X86_FEATURE_TDX_GUEST) everywhere?
is_tdx_guest() is also implemented/used in compressed
code (which uses native_cpuid calls). I don't think
we can use cpu_feature_enabled(X86_FEATURE_TDX_GUEST) in
compressed code right? Also is_tdx_guest() looks easy
to read and use.
OK, but how many of the is_tdx_guest() uses are in the compressed code?
Why has its use spread beyond that?
Its only used in handling in/out instructions in compressed code. But this
code shared with in/out handling on non-compressed code.
#define __out(bwl, bw) \
do { \
if (is_tdx_guest()) { \
asm volatile("call tdg_out" #bwl : : \
"a"(value), "d"(port)); \
} else { \
asm volatile("out" #bwl " %" #bw "0, %w1" : : \
"a"(value), "Nd"(port)); \
} \
} while (0)
#define __in(bwl, bw) \
do { \
if (is_tdx_guest()) { \
asm volatile("call tdg_in" #bwl : \
"=a"(value) : "d"(port)); \
} else { \
asm volatile("in" #bwl " %w1, %" #bw "0" : \
"=a"(value) : "Nd"(port)); \
} \
} while (0)
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
