x86/fpu: Remove irq_ts_save() and irq_ts_restore()

Now that lazy FPU is gone, we don't use CR0.TS (except possibly in
KVM guest mode).  Remove irq_ts_save(), irq_ts_restore(), and all of
their callers.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm list <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/70b9b9e7ba70659bedcb08aba63d0f9214f338f2.1477951965.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

5 files changed, 4 insertions, 84 deletions

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index 1429a7c..0877ae0 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -27,16 +27,6 @@ extern void kernel_fpu_end(void);
 extern bool irq_fpu_usable(void);
 
 /*
- * Some instructions like VIA's padlock instructions generate a spurious
- * DNA fault but don't modify SSE registers. And these instructions
- * get used from interrupt context as well. To prevent these kernel instructions
- * in interrupt context interacting wrongly with other user/kernel fpu usage, we
- * should use them only in the context of irq_ts_save/restore()
- */
-extern int  irq_ts_save(void);
-extern void irq_ts_restore(int TS_state);
-
-/*
  * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
  *
  * If 'feature_name' is set then put a human-readable description of
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 52f56844..7d8e262 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -138,35 +138,6 @@ void kernel_fpu_end(void)
 EXPORT_SYMBOL_GPL(kernel_fpu_end);
 
 /*
- * CR0::TS save/restore functions:
- */
-int irq_ts_save(void)
-{
-	/*
-	 * If in process context and not atomic, we can take a spurious DNA fault.
-	 * Otherwise, doing clts() in process context requires disabling preemption
-	 * or some heavy lifting like kernel_fpu_begin()
-	 */
-	if (!in_atomic())
-		return 0;
-
-	if (read_cr0() & X86_CR0_TS) {
-		clts();
-		return 1;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(irq_ts_save);
-
-void irq_ts_restore(int TS_state)
-{
-	if (TS_state)
-		stts();
-}
-EXPORT_SYMBOL_GPL(irq_ts_restore);
-
-/*
  * Save the FPU state (mark it for reload if necessary):
  *
  * This only ever gets called for the current task.
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index 44ce806..d1f5bb5 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -70,21 +70,17 @@ enum {
  * until we have 4 bytes, thus returning a u32 at a time,
  * instead of the current u8-at-a-time.
  *
- * Padlock instructions can generate a spurious DNA fault, so
- * we have to call them in the context of irq_ts_save/restore()
+ * Padlock instructions can generate a spurious DNA fault, but the
+ * kernel doesn't use CR0.TS, so this doesn't matter.
  */
 
 static inline u32 xstore(u32 *addr, u32 edx_in)
 {
 	u32 eax_out;
-	int ts_state;
-
-	ts_state = irq_ts_save();
 
 	asm(".byte 0x0F,0xA7,0xC0 /* xstore %%edi (addr=%0) */"
 		: "=m" (*addr), "=a" (eax_out), "+d" (edx_in), "+D" (addr));
 
-	irq_ts_restore(ts_state);
 	return eax_out;
 }
 
diff --git a/drivers/crypto/padlock-aes.c b/drivers/crypto/padlock-aes.c
index 441e86b..b386974 100644
--- a/drivers/crypto/padlock-aes.c
+++ b/drivers/crypto/padlock-aes.c
@@ -183,8 +183,8 @@ static inline void padlock_store_cword(struct cword *cword)
 
 /*
  * While the padlock instructions don't use FP/SSE registers, they
- * generate a spurious DNA fault when cr0.ts is '1'. These instructions
- * should be used only inside the irq_ts_save/restore() context
+ * generate a spurious DNA fault when CR0.TS is '1'.  Fortunately,
+ * the kernel doesn't use CR0.TS.
  */
 
 static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
@@ -298,24 +298,18 @@ static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 {
 	struct aes_ctx *ctx = aes_ctx(tfm);
-	int ts_state;
 
 	padlock_reset_key(&ctx->cword.encrypt);
-	ts_state = irq_ts_save();
 	ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
-	irq_ts_restore(ts_state);
 	padlock_store_cword(&ctx->cword.encrypt);
 }
 
 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 {
 	struct aes_ctx *ctx = aes_ctx(tfm);
-	int ts_state;
 
 	padlock_reset_key(&ctx->cword.encrypt);
-	ts_state = irq_ts_save();
 	ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
-	irq_ts_restore(ts_state);
 	padlock_store_cword(&ctx->cword.encrypt);
 }
 
@@ -346,14 +340,12 @@ static int ecb_aes_encrypt(struct blkcipher_desc *desc,
 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 	struct blkcipher_walk walk;
 	int err;
-	int ts_state;
 
 	padlock_reset_key(&ctx->cword.encrypt);
 
 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt(desc, &walk);
 
-	ts_state = irq_ts_save();
 	while ((nbytes = walk.nbytes)) {
 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
 				   ctx->E, &ctx->cword.encrypt,
@@ -361,7 +353,6 @@ static int ecb_aes_encrypt(struct blkcipher_desc *desc,
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	irq_ts_restore(ts_state);
 
 	padlock_store_cword(&ctx->cword.encrypt);
 
@@ -375,14 +366,12 @@ static int ecb_aes_decrypt(struct blkcipher_desc *desc,
 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 	struct blkcipher_walk walk;
 	int err;
-	int ts_state;
 
 	padlock_reset_key(&ctx->cword.decrypt);
 
 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt(desc, &walk);
 
-	ts_state = irq_ts_save();
 	while ((nbytes = walk.nbytes)) {
 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
 				   ctx->D, &ctx->cword.decrypt,
@@ -390,7 +379,6 @@ static int ecb_aes_decrypt(struct blkcipher_desc *desc,
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	irq_ts_restore(ts_state);
 
 	padlock_store_cword(&ctx->cword.encrypt);
 
@@ -425,14 +413,12 @@ static int cbc_aes_encrypt(struct blkcipher_desc *desc,
 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 	struct blkcipher_walk walk;
 	int err;
-	int ts_state;
 
 	padlock_reset_key(&ctx->cword.encrypt);
 
 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt(desc, &walk);
 
-	ts_state = irq_ts_save();
 	while ((nbytes = walk.nbytes)) {
 		u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
 					    walk.dst.virt.addr, ctx->E,
@@ -442,7 +428,6 @@ static int cbc_aes_encrypt(struct blkcipher_desc *desc,
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	irq_ts_restore(ts_state);
 
 	padlock_store_cword(&ctx->cword.decrypt);
 
@@ -456,14 +441,12 @@ static int cbc_aes_decrypt(struct blkcipher_desc *desc,
 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 	struct blkcipher_walk walk;
 	int err;
-	int ts_state;
 
 	padlock_reset_key(&ctx->cword.encrypt);
 
 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt(desc, &walk);
 
-	ts_state = irq_ts_save();
 	while ((nbytes = walk.nbytes)) {
 		padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
 				   ctx->D, walk.iv, &ctx->cword.decrypt,
@@ -472,8 +455,6 @@ static int cbc_aes_decrypt(struct blkcipher_desc *desc,
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
 
-	irq_ts_restore(ts_state);
-
 	padlock_store_cword(&ctx->cword.encrypt);
 
 	return err;
diff --git a/drivers/crypto/padlock-sha.c b/drivers/crypto/padlock-sha.c
index 8c5f906..bc72d20 100644
--- a/drivers/crypto/padlock-sha.c
+++ b/drivers/crypto/padlock-sha.c
@@ -89,7 +89,6 @@ static int padlock_sha1_finup(struct shash_desc *desc, const u8 *in,
 	struct sha1_state state;
 	unsigned int space;
 	unsigned int leftover;
-	int ts_state;
 	int err;
 
 	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
@@ -120,14 +119,11 @@ static int padlock_sha1_finup(struct shash_desc *desc, const u8 *in,
 
 	memcpy(result, &state.state, SHA1_DIGEST_SIZE);
 
-	/* prevent taking the spurious DNA fault with padlock. */
-	ts_state = irq_ts_save();
 	asm volatile (".byte 0xf3,0x0f,0xa6,0xc8" /* rep xsha1 */
 		      : \
 		      : "c"((unsigned long)state.count + count), \
 			"a"((unsigned long)state.count), \
 			"S"(in), "D"(result));
-	irq_ts_restore(ts_state);
 
 	padlock_output_block((uint32_t *)result, (uint32_t *)out, 5);
 
@@ -155,7 +151,6 @@ static int padlock_sha256_finup(struct shash_desc *desc, const u8 *in,
 	struct sha256_state state;
 	unsigned int space;
 	unsigned int leftover;
-	int ts_state;
 	int err;
 
 	dctx->fallback.flags = desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
@@ -186,14 +181,11 @@ static int padlock_sha256_finup(struct shash_desc *desc, const u8 *in,
 
 	memcpy(result, &state.state, SHA256_DIGEST_SIZE);
 
-	/* prevent taking the spurious DNA fault with padlock. */
-	ts_state = irq_ts_save();
 	asm volatile (".byte 0xf3,0x0f,0xa6,0xd0" /* rep xsha256 */
 		      : \
 		      : "c"((unsigned long)state.count + count), \
 			"a"((unsigned long)state.count), \
 			"S"(in), "D"(result));
-	irq_ts_restore(ts_state);
 
 	padlock_output_block((uint32_t *)result, (uint32_t *)out, 8);
 
@@ -312,7 +304,6 @@ static int padlock_sha1_update_nano(struct shash_desc *desc,
 	u8 buf[128 + PADLOCK_ALIGNMENT - STACK_ALIGN] __attribute__
 		((aligned(STACK_ALIGN)));
 	u8 *dst = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
-	int ts_state;
 
 	partial = sctx->count & 0x3f;
 	sctx->count += len;
@@ -328,23 +319,19 @@ static int padlock_sha1_update_nano(struct shash_desc *desc,
 			memcpy(sctx->buffer + partial, data,
 				done + SHA1_BLOCK_SIZE);
 			src = sctx->buffer;
-			ts_state = irq_ts_save();
 			asm volatile (".byte 0xf3,0x0f,0xa6,0xc8"
 			: "+S"(src), "+D"(dst) \
 			: "a"((long)-1), "c"((unsigned long)1));
-			irq_ts_restore(ts_state);
 			done += SHA1_BLOCK_SIZE;
 			src = data + done;
 		}
 
 		/* Process the left bytes from the input data */
 		if (len - done >= SHA1_BLOCK_SIZE) {
-			ts_state = irq_ts_save();
 			asm volatile (".byte 0xf3,0x0f,0xa6,0xc8"
 			: "+S"(src), "+D"(dst)
 			: "a"((long)-1),
 			"c"((unsigned long)((len - done) / SHA1_BLOCK_SIZE)));
-			irq_ts_restore(ts_state);
 			done += ((len - done) - (len - done) % SHA1_BLOCK_SIZE);
 			src = data + done;
 		}
@@ -401,7 +388,6 @@ static int padlock_sha256_update_nano(struct shash_desc *desc, const u8 *data,
 	u8 buf[128 + PADLOCK_ALIGNMENT - STACK_ALIGN] __attribute__
 		((aligned(STACK_ALIGN)));
 	u8 *dst = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
-	int ts_state;
 
 	partial = sctx->count & 0x3f;
 	sctx->count += len;
@@ -417,23 +403,19 @@ static int padlock_sha256_update_nano(struct shash_desc *desc, const u8 *data,
 			memcpy(sctx->buf + partial, data,
 				done + SHA256_BLOCK_SIZE);
 			src = sctx->buf;
-			ts_state = irq_ts_save();
 			asm volatile (".byte 0xf3,0x0f,0xa6,0xd0"
 			: "+S"(src), "+D"(dst)
 			: "a"((long)-1), "c"((unsigned long)1));
-			irq_ts_restore(ts_state);
 			done += SHA256_BLOCK_SIZE;
 			src = data + done;
 		}
 
 		/* Process the left bytes from input data*/
 		if (len - done >= SHA256_BLOCK_SIZE) {
-			ts_state = irq_ts_save();
 			asm volatile (".byte 0xf3,0x0f,0xa6,0xd0"
 			: "+S"(src), "+D"(dst)
 			: "a"((long)-1),
 			"c"((unsigned long)((len - done) / 64)));
-			irq_ts_restore(ts_state);
 			done += ((len - done) - (len - done) % 64);
 			src = data + done;
 		}