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[cpuid] Allow input %ecx value to be specified

For some CPUID leaves (e.g. %eax=0x00000004), the result depends on
the input value of %ecx.  Allow this subfunction number to be
specified as a parameter to the cpuid() wrapper.

The subfunction number is exposed via the ${cpuid/...} settings
mechanism using the syntax

  ${cpuid/<subfunction>.0x40.<register>.<function>}

e.g.

  ${cpuid/0.0x40.0.0x0000000b}
  ${cpuid/1.0x40.0.0x0000000b}

to retrieve the CPU topology information.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
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mcb30 committed Jun 15, 2017
1 parent c8cb867 commit a6a5825f8d658834610de31b7b9be2e7d0a8804e
@@ -84,7 +84,7 @@ int cpuid_supported ( uint32_t function ) {
return rc;

/* Find highest supported function number within this family */
cpuid ( ( function & CPUID_EXTENDED ), &max_function, &discard_b,
cpuid ( ( function & CPUID_EXTENDED ), 0, &max_function, &discard_b,
&discard_c, &discard_d );

/* Fail if maximum function number is meaningless (e.g. if we
@@ -125,7 +125,7 @@ static void x86_intel_features ( struct x86_features *features ) {
}

/* Get features */
cpuid ( CPUID_FEATURES, &discard_a, &discard_b,
cpuid ( CPUID_FEATURES, 0, &discard_a, &discard_b,
&features->intel.ecx, &features->intel.edx );
DBGC ( features, "CPUID Intel features: %%ecx=%08x, %%edx=%08x\n",
features->intel.ecx, features->intel.edx );
@@ -149,7 +149,7 @@ static void x86_amd_features ( struct x86_features *features ) {
}

/* Get features */
cpuid ( CPUID_AMD_FEATURES, &discard_a, &discard_b,
cpuid ( CPUID_AMD_FEATURES, 0, &discard_a, &discard_b,
&features->amd.ecx, &features->amd.edx );
DBGC ( features, "CPUID AMD features: %%ecx=%08x, %%edx=%08x\n",
features->amd.ecx, features->amd.edx );
@@ -37,10 +37,11 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* CPUID settings are numerically encoded as:
*
* Bit 31 Extended function
* Bits 30-28 Unused
* Bits 27-24 Number of consecutive functions to call, minus one
* Bits 30-24 (bit 22 = 1) Subfunction number
* (bit 22 = 0) Number of consecutive functions to call, minus one
* Bit 23 Return result as little-endian (used for strings)
* Bits 22-18 Unused
* Bit 22 Interpret bits 30-24 as a subfunction number
* Bits 21-18 Unused
* Bits 17-16 Number of registers in register array, minus one
* Bits 15-8 Array of register indices. First entry in array is in
* bits 9-8. Indices are 0-%eax, 1-%ebx, 2-%ecx, 3-%edx.
@@ -50,6 +51,11 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* extracting a single register from a single function to be encoded
* using "cpuid/<register>.<function>", e.g. "cpuid/2.0x80000001" to
* retrieve the value of %ecx from calling CPUID with %eax=0x80000001.
*
* A subfunction (i.e. an input value for %ecx) may be specified using
* "cpuid/<subfunction>.0x40.<register>.<function>". This slightly
* cumbersome syntax is required in order to maintain backwards
* compatibility with older scripts.
*/

/** CPUID setting tag register indices */
@@ -60,34 +66,32 @@ enum cpuid_registers {
CPUID_EDX = 3,
};

/** CPUID setting tag flags */
enum cpuid_flags {
CPUID_LITTLE_ENDIAN = 0x00800000UL,
CPUID_USE_SUBFUNCTION = 0x00400000UL,
};

/**
* Construct CPUID setting tag
*
* @v function Starting function number
* @v num_functions Number of consecutive functions
* @v little_endian Return result as little-endian
* @v subfunction Subfunction, or number of consecutive functions minus 1
* @v flags Flags
* @v num_registers Number of registers in register array
* @v register1 First register in register array (or zero, if empty)
* @v register2 Second register in register array (or zero, if empty)
* @v register3 Third register in register array (or zero, if empty)
* @v register4 Fourth register in register array (or zero, if empty)
* @ret tag Setting tag
*/
#define CPUID_TAG( function, num_functions, little_endian, num_registers, \
register1, register2, register3, register4 ) \
( (function) | ( ( (num_functions) - 1 ) << 24 ) | \
( (little_endian) << 23 ) | ( ( (num_registers) - 1) << 16 ) | \
( (register1) << 8 ) | ( (register2) << 10 ) | \
#define CPUID_TAG( function, subfunction, flags, num_registers, \
register1, register2, register3, register4 ) \
( (function) | ( (subfunction) << 24 ) | (flags) | \
( ( (num_registers) - 1 ) << 16 ) | \
( (register1) << 8 ) | ( (register2) << 10 ) | \
( (register3) << 12 ) | ( (register4) << 14 ) )

/**
* Extract endianness from CPUID setting tag
*
* @v tag Setting tag
* @ret little_endian Result should be returned as little-endian
*/
#define CPUID_LITTLE_ENDIAN( tag ) ( (tag) & 0x00800000UL )

/**
* Extract starting function number from CPUID setting tag
*
@@ -97,12 +101,12 @@ enum cpuid_registers {
#define CPUID_FUNCTION( tag ) ( (tag) & 0x800000ffUL )

/**
* Extract number of consecutive functions from CPUID setting tag
* Extract subfunction number from CPUID setting tag
*
* @v tag Setting tag
* @ret num_functions Number of consecutive functions
* @ret subfunction Subfunction number
*/
#define CPUID_NUM_FUNCTIONS( tag ) ( ( ( (tag) >> 24 ) & 0xf ) + 1 )
#define CPUID_SUBFUNCTION( tag ) ( ( (tag) >> 24 ) & 0x7f )

/**
* Extract register array from CPUID setting tag
@@ -149,6 +153,7 @@ static int cpuid_settings_fetch ( struct settings *settings,
struct setting *setting,
void *data, size_t len ) {
uint32_t function;
uint32_t subfunction;
uint32_t num_functions;
uint32_t registers;
uint32_t num_registers;
@@ -160,7 +165,13 @@ static int cpuid_settings_fetch ( struct settings *settings,

/* Call each function in turn */
function = CPUID_FUNCTION ( setting->tag );
num_functions = CPUID_NUM_FUNCTIONS ( setting->tag );
subfunction = CPUID_SUBFUNCTION ( setting->tag );
if ( setting->tag & CPUID_USE_SUBFUNCTION ) {
num_functions = 1;
} else {
num_functions = ( subfunction + 1 );
subfunction = 0;
}
for ( ; num_functions-- ; function++ ) {

/* Fail if this function is not supported */
@@ -171,17 +182,17 @@ static int cpuid_settings_fetch ( struct settings *settings,
}

/* Issue CPUID */
cpuid ( function, &buf[CPUID_EAX], &buf[CPUID_EBX],
&buf[CPUID_ECX], &buf[CPUID_EDX] );
DBGC ( settings, "CPUID %#08x => %#08x:%#08x:%#08x:%#08x\n",
function, buf[0], buf[1], buf[2], buf[3] );
cpuid ( function, subfunction, &buf[CPUID_EAX],
&buf[CPUID_EBX], &buf[CPUID_ECX], &buf[CPUID_EDX] );
DBGC ( settings, "CPUID %#08x:%x => %#08x:%#08x:%#08x:%#08x\n",
function, subfunction, buf[0], buf[1], buf[2], buf[3] );

/* Copy results to buffer */
registers = CPUID_REGISTERS ( setting->tag );
num_registers = CPUID_NUM_REGISTERS ( setting->tag );
for ( ; num_registers-- ; registers >>= 2 ) {
output = buf[ registers & 0x3 ];
if ( ! CPUID_LITTLE_ENDIAN ( setting->tag ) )
if ( ! ( setting->tag & CPUID_LITTLE_ENDIAN ) )
output = cpu_to_be32 ( output );
frag_len = sizeof ( output );
if ( frag_len > len )
@@ -237,7 +248,7 @@ const struct setting cpuvendor_setting __setting ( SETTING_HOST_EXTRA,
cpuvendor ) = {
.name = "cpuvendor",
.description = "CPU vendor",
.tag = CPUID_TAG ( CPUID_VENDOR_ID, 1, 1, 3,
.tag = CPUID_TAG ( CPUID_VENDOR_ID, 0, CPUID_LITTLE_ENDIAN, 3,
CPUID_EBX, CPUID_EDX, CPUID_ECX, 0 ),
.type = &setting_type_string,
.scope = &cpuid_settings_scope,
@@ -248,7 +259,7 @@ const struct setting cpumodel_setting __setting ( SETTING_HOST_EXTRA,
cpumodel ) = {
.name = "cpumodel",
.description = "CPU model",
.tag = CPUID_TAG ( CPUID_MODEL, 3, 1, 4,
.tag = CPUID_TAG ( CPUID_MODEL, 2, CPUID_LITTLE_ENDIAN, 4,
CPUID_EAX, CPUID_EBX, CPUID_ECX, CPUID_EDX ),
.type = &setting_type_string,
.scope = &cpuid_settings_scope,
@@ -132,7 +132,7 @@ static int rdtsc_probe ( void ) {
strerror ( rc ) );
return rc;
}
cpuid ( CPUID_APM, &discard_a, &discard_b, &discard_c, &apm );
cpuid ( CPUID_APM, 0, &discard_a, &discard_b, &discard_c, &apm );
if ( ! ( apm & CPUID_APM_EDX_TSC_INVARIANT ) ) {
DBGC ( colour, "RDTSC has non-invariant TSC (%#08x)\n",
apm );
@@ -170,7 +170,7 @@ static int hv_check_hv ( void ) {
}

/* Check that hypervisor is Hyper-V */
cpuid ( HV_CPUID_INTERFACE_ID, &interface_id, &discard_ebx,
cpuid ( HV_CPUID_INTERFACE_ID, 0, &interface_id, &discard_ebx,
&discard_ecx, &discard_edx );
if ( interface_id != HV_INTERFACE_ID ) {
DBGC ( HV_INTERFACE_ID, "HV not running in Hyper-V (interface "
@@ -194,7 +194,7 @@ static int hv_check_features ( struct hv_hypervisor *hv ) {
uint32_t discard_edx;

/* Check that required features and privileges are available */
cpuid ( HV_CPUID_FEATURES, &available, &permissions, &discard_ecx,
cpuid ( HV_CPUID_FEATURES, 0, &available, &permissions, &discard_ecx,
&discard_edx );
if ( ! ( available & HV_FEATURES_AVAIL_HYPERCALL_MSR ) ) {
DBGC ( hv, "HV %p has no hypercall MSRs (features %08x:%08x)\n",
@@ -253,10 +253,10 @@ static void hv_map_hypercall ( struct hv_hypervisor *hv ) {
wrmsr ( HV_X64_MSR_GUEST_OS_ID, guest_os_id );

/* Get hypervisor system identity (for debugging) */
cpuid ( HV_CPUID_VENDOR_ID, &discard_eax, &vendor_id.ebx,
cpuid ( HV_CPUID_VENDOR_ID, 0, &discard_eax, &vendor_id.ebx,
&vendor_id.ecx, &vendor_id.edx );
vendor_id.text[ sizeof ( vendor_id.text ) - 1 ] = '\0';
cpuid ( HV_CPUID_HYPERVISOR_ID, &build, &version, &discard_ecx,
cpuid ( HV_CPUID_HYPERVISOR_ID, 0, &build, &version, &discard_ecx,
&discard_edx );
DBGC ( hv, "HV %p detected \"%s\" version %d.%d build %d\n", hv,
vendor_id.text, ( version >> 16 ), ( version & 0xffff ), build );
@@ -735,7 +735,7 @@ static int hv_timer_probe ( void ) {
return rc;

/* Check for available reference counter */
cpuid ( HV_CPUID_FEATURES, &available, &discard_ebx, &discard_ecx,
cpuid ( HV_CPUID_FEATURES, 0, &available, &discard_ebx, &discard_ecx,
&discard_edx );
if ( ! ( available & HV_FEATURES_AVAIL_TIME_REF_COUNT_MSR ) ) {
DBGC ( HV_INTERFACE_ID, "HV has no time reference counter\n" );
@@ -66,12 +66,12 @@ static int hvm_cpuid_base ( struct hvm_device *hvm ) {
/* Scan for magic signature */
for ( base = HVM_CPUID_MIN ; base <= HVM_CPUID_MAX ;
base += HVM_CPUID_STEP ) {
cpuid ( base, &discard_eax, &signature.ebx, &signature.ecx,
cpuid ( base, 0, &discard_eax, &signature.ebx, &signature.ecx,
&signature.edx );
if ( memcmp ( &signature, HVM_CPUID_MAGIC,
sizeof ( signature ) ) == 0 ) {
hvm->cpuid_base = base;
cpuid ( ( base + HVM_CPUID_VERSION ), &version,
cpuid ( ( base + HVM_CPUID_VERSION ), 0, &version,
&discard_ebx, &discard_ecx, &discard_edx );
DBGC2 ( hvm, "HVM using CPUID base %#08x (v%d.%d)\n",
base, ( version >> 16 ), ( version & 0xffff ) );
@@ -101,7 +101,7 @@ static int hvm_map_hypercall ( struct hvm_device *hvm ) {
int rc;

/* Get number of hypercall pages and MSR to use */
cpuid ( ( hvm->cpuid_base + HVM_CPUID_PAGES ), &pages, &msr,
cpuid ( ( hvm->cpuid_base + HVM_CPUID_PAGES ), 0, &pages, &msr,
&discard_ecx, &discard_edx );

/* Allocate pages */
@@ -66,19 +66,20 @@ struct x86_features {
/**
* Issue CPUID instruction
*
* @v function CPUID function
* @v function CPUID function (input via %eax)
* @v subfunction CPUID subfunction (input via %ecx)
* @v eax Output via %eax
* @v ebx Output via %ebx
* @v ecx Output via %ecx
* @v edx Output via %edx
*/
static inline __attribute__ (( always_inline )) void
cpuid ( uint32_t function, uint32_t *eax, uint32_t *ebx, uint32_t *ecx,
uint32_t *edx ) {
cpuid ( uint32_t function, uint32_t subfunction, uint32_t *eax, uint32_t *ebx,
uint32_t *ecx, uint32_t *edx ) {

__asm__ ( "cpuid"
: "=a" ( *eax ), "=b" ( *ebx ), "=c" ( *ecx ), "=d" ( *edx )
: "0" ( function ) );
: "0" ( function ), "2" ( subfunction ) );
}

extern int cpuid_supported ( uint32_t function );

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