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x86/cpu/intel: Detect TME keyid bits before setting MTRR mask registers
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MKTME repurposes the high bit of physical address to key id for encryption
key and, even though MAXPHYADDR in CPUID[0x80000008] remains the same,
the valid bits in the MTRR mask register are based on the reduced number
of physical address bits.

detect_tme() in arch/x86/kernel/cpu/intel.c detects TME and subtracts
it from the total usable physical bits, but it is called too late.
Move the call to early_init_intel() so that it is called in setup_arch(),
before MTRRs are setup.

This fixes boot on TDX-enabled systems, which until now only worked with
"disable_mtrr_cleanup".  Without the patch, the values written to the
MTRRs mask registers were 52-bit wide (e.g. 0x000fffff_80000800) and
the writes failed; with the patch, the values are 46-bit wide, which
matches the reduced MAXPHYADDR that is shown in /proc/cpuinfo.

Reported-by: Zixi Chen <zixchen@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240131230902.1867092-3-pbonzini%40redhat.com
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Paolo Bonzini authored and Dave Hansen committed Feb 26, 2024
1 parent 9a45819 commit 6890cb1
Showing 1 changed file with 91 additions and 87 deletions.
178 changes: 91 additions & 87 deletions arch/x86/kernel/cpu/intel.c
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Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,90 @@ static bool bad_spectre_microcode(struct cpuinfo_x86 *c)
return false;
}

#define MSR_IA32_TME_ACTIVATE 0x982

/* Helpers to access TME_ACTIVATE MSR */
#define TME_ACTIVATE_LOCKED(x) (x & 0x1)
#define TME_ACTIVATE_ENABLED(x) (x & 0x2)

#define TME_ACTIVATE_POLICY(x) ((x >> 4) & 0xf) /* Bits 7:4 */
#define TME_ACTIVATE_POLICY_AES_XTS_128 0

#define TME_ACTIVATE_KEYID_BITS(x) ((x >> 32) & 0xf) /* Bits 35:32 */

#define TME_ACTIVATE_CRYPTO_ALGS(x) ((x >> 48) & 0xffff) /* Bits 63:48 */
#define TME_ACTIVATE_CRYPTO_AES_XTS_128 1

/* Values for mktme_status (SW only construct) */
#define MKTME_ENABLED 0
#define MKTME_DISABLED 1
#define MKTME_UNINITIALIZED 2
static int mktme_status = MKTME_UNINITIALIZED;

static void detect_tme_early(struct cpuinfo_x86 *c)
{
u64 tme_activate, tme_policy, tme_crypto_algs;
int keyid_bits = 0, nr_keyids = 0;
static u64 tme_activate_cpu0 = 0;

rdmsrl(MSR_IA32_TME_ACTIVATE, tme_activate);

if (mktme_status != MKTME_UNINITIALIZED) {
if (tme_activate != tme_activate_cpu0) {
/* Broken BIOS? */
pr_err_once("x86/tme: configuration is inconsistent between CPUs\n");
pr_err_once("x86/tme: MKTME is not usable\n");
mktme_status = MKTME_DISABLED;

/* Proceed. We may need to exclude bits from x86_phys_bits. */
}
} else {
tme_activate_cpu0 = tme_activate;
}

if (!TME_ACTIVATE_LOCKED(tme_activate) || !TME_ACTIVATE_ENABLED(tme_activate)) {
pr_info_once("x86/tme: not enabled by BIOS\n");
mktme_status = MKTME_DISABLED;
return;
}

if (mktme_status != MKTME_UNINITIALIZED)
goto detect_keyid_bits;

pr_info("x86/tme: enabled by BIOS\n");

tme_policy = TME_ACTIVATE_POLICY(tme_activate);
if (tme_policy != TME_ACTIVATE_POLICY_AES_XTS_128)
pr_warn("x86/tme: Unknown policy is active: %#llx\n", tme_policy);

tme_crypto_algs = TME_ACTIVATE_CRYPTO_ALGS(tme_activate);
if (!(tme_crypto_algs & TME_ACTIVATE_CRYPTO_AES_XTS_128)) {
pr_err("x86/mktme: No known encryption algorithm is supported: %#llx\n",
tme_crypto_algs);
mktme_status = MKTME_DISABLED;
}
detect_keyid_bits:
keyid_bits = TME_ACTIVATE_KEYID_BITS(tme_activate);
nr_keyids = (1UL << keyid_bits) - 1;
if (nr_keyids) {
pr_info_once("x86/mktme: enabled by BIOS\n");
pr_info_once("x86/mktme: %d KeyIDs available\n", nr_keyids);
} else {
pr_info_once("x86/mktme: disabled by BIOS\n");
}

if (mktme_status == MKTME_UNINITIALIZED) {
/* MKTME is usable */
mktme_status = MKTME_ENABLED;
}

/*
* KeyID bits effectively lower the number of physical address
* bits. Update cpuinfo_x86::x86_phys_bits accordingly.
*/
c->x86_phys_bits -= keyid_bits;
}

static void early_init_intel(struct cpuinfo_x86 *c)
{
u64 misc_enable;
Expand Down Expand Up @@ -322,6 +406,13 @@ static void early_init_intel(struct cpuinfo_x86 *c)
*/
if (detect_extended_topology_early(c) < 0)
detect_ht_early(c);

/*
* Adjust the number of physical bits early because it affects the
* valid bits of the MTRR mask registers.
*/
if (cpu_has(c, X86_FEATURE_TME))
detect_tme_early(c);
}

static void bsp_init_intel(struct cpuinfo_x86 *c)
Expand Down Expand Up @@ -482,90 +573,6 @@ static void srat_detect_node(struct cpuinfo_x86 *c)
#endif
}

#define MSR_IA32_TME_ACTIVATE 0x982

/* Helpers to access TME_ACTIVATE MSR */
#define TME_ACTIVATE_LOCKED(x) (x & 0x1)
#define TME_ACTIVATE_ENABLED(x) (x & 0x2)

#define TME_ACTIVATE_POLICY(x) ((x >> 4) & 0xf) /* Bits 7:4 */
#define TME_ACTIVATE_POLICY_AES_XTS_128 0

#define TME_ACTIVATE_KEYID_BITS(x) ((x >> 32) & 0xf) /* Bits 35:32 */

#define TME_ACTIVATE_CRYPTO_ALGS(x) ((x >> 48) & 0xffff) /* Bits 63:48 */
#define TME_ACTIVATE_CRYPTO_AES_XTS_128 1

/* Values for mktme_status (SW only construct) */
#define MKTME_ENABLED 0
#define MKTME_DISABLED 1
#define MKTME_UNINITIALIZED 2
static int mktme_status = MKTME_UNINITIALIZED;

static void detect_tme(struct cpuinfo_x86 *c)
{
u64 tme_activate, tme_policy, tme_crypto_algs;
int keyid_bits = 0, nr_keyids = 0;
static u64 tme_activate_cpu0 = 0;

rdmsrl(MSR_IA32_TME_ACTIVATE, tme_activate);

if (mktme_status != MKTME_UNINITIALIZED) {
if (tme_activate != tme_activate_cpu0) {
/* Broken BIOS? */
pr_err_once("x86/tme: configuration is inconsistent between CPUs\n");
pr_err_once("x86/tme: MKTME is not usable\n");
mktme_status = MKTME_DISABLED;

/* Proceed. We may need to exclude bits from x86_phys_bits. */
}
} else {
tme_activate_cpu0 = tme_activate;
}

if (!TME_ACTIVATE_LOCKED(tme_activate) || !TME_ACTIVATE_ENABLED(tme_activate)) {
pr_info_once("x86/tme: not enabled by BIOS\n");
mktme_status = MKTME_DISABLED;
return;
}

if (mktme_status != MKTME_UNINITIALIZED)
goto detect_keyid_bits;

pr_info("x86/tme: enabled by BIOS\n");

tme_policy = TME_ACTIVATE_POLICY(tme_activate);
if (tme_policy != TME_ACTIVATE_POLICY_AES_XTS_128)
pr_warn("x86/tme: Unknown policy is active: %#llx\n", tme_policy);

tme_crypto_algs = TME_ACTIVATE_CRYPTO_ALGS(tme_activate);
if (!(tme_crypto_algs & TME_ACTIVATE_CRYPTO_AES_XTS_128)) {
pr_err("x86/mktme: No known encryption algorithm is supported: %#llx\n",
tme_crypto_algs);
mktme_status = MKTME_DISABLED;
}
detect_keyid_bits:
keyid_bits = TME_ACTIVATE_KEYID_BITS(tme_activate);
nr_keyids = (1UL << keyid_bits) - 1;
if (nr_keyids) {
pr_info_once("x86/mktme: enabled by BIOS\n");
pr_info_once("x86/mktme: %d KeyIDs available\n", nr_keyids);
} else {
pr_info_once("x86/mktme: disabled by BIOS\n");
}

if (mktme_status == MKTME_UNINITIALIZED) {
/* MKTME is usable */
mktme_status = MKTME_ENABLED;
}

/*
* KeyID bits effectively lower the number of physical address
* bits. Update cpuinfo_x86::x86_phys_bits accordingly.
*/
c->x86_phys_bits -= keyid_bits;
}

static void init_cpuid_fault(struct cpuinfo_x86 *c)
{
u64 msr;
Expand Down Expand Up @@ -702,9 +709,6 @@ static void init_intel(struct cpuinfo_x86 *c)

init_ia32_feat_ctl(c);

if (cpu_has(c, X86_FEATURE_TME))
detect_tme(c);

init_intel_misc_features(c);

split_lock_init();
Expand Down

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