s390/fpu: convert FPU CIF flag to regular TIF flag

The FPU state, as represented by the CIF_FPU flag reflects the FPU state of
a task, not the CPU it is running on. Therefore convert the flag to a
regular TIF flag.

This removes the magic in switch_to() where a save_fpu_regs() call for the
currently (previous) running task sets the per-cpu CIF_FPU flag, which is
required to restore FPU register contents of the next task, when it returns
to user space.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/include/asm/entry-common.h b/arch/s390/include/asm/entry-common.h
index a1dbab19c0bd0f68488cb5d159eac89ea3a9c0b1..e479d39e14459f159627213f3198f8b3fba07feb 100644 (file)
--- a/arch/s390/include/asm/entry-common.h
+++ b/arch/s390/include/asm/entry-common.h
@@ -41,7 +41,7 @@ static __always_inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
 
 static __always_inline void arch_exit_to_user_mode(void)
 {
-       if (test_cpu_flag(CIF_FPU))
+       if (test_thread_flag(TIF_FPU))
                __load_fpu_regs();
 
        if (IS_ENABLED(CONFIG_DEBUG_ENTRY))

diff --git a/arch/s390/include/asm/fpu.h b/arch/s390/include/asm/fpu.h
index be85c28cdcde667b35bb8bb8dea2545c0a07497a..3f076172a28300dc1046d81fb6e1d2f75e751ae1 100644 (file)
--- a/arch/s390/include/asm/fpu.h
+++ b/arch/s390/include/asm/fpu.h
@@ -148,7 +148,7 @@ static inline void kernel_fpu_begin(struct kernel_fpu *state, u32 flags)
 {
        preempt_disable();
        state->mask = S390_lowcore.fpu_flags;
-       if (!test_cpu_flag(CIF_FPU)) {
+       if (!test_thread_flag(TIF_FPU)) {
                /* Save user space FPU state and register contents */
                save_fpu_regs();
        } else if (state->mask & flags) {

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index a422a2cf9d05bc9cf34cecc07b2f5c6e1b560a4d..f25617cbc49eb4f7c55833f9073d9adef86abd01 100644 (file)
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -15,13 +15,11 @@
 #include <linux/bits.h>
 
 #define CIF_NOHZ_DELAY         2       /* delay HZ disable for a tick */
-#define CIF_FPU                        3       /* restore FPU registers */
 #define CIF_ENABLED_WAIT       5       /* in enabled wait state */
 #define CIF_MCCK_GUEST         6       /* machine check happening in guest */
 #define CIF_DEDICATED_CPU      7       /* this CPU is dedicated */
 
 #define _CIF_NOHZ_DELAY                BIT(CIF_NOHZ_DELAY)
-#define _CIF_FPU               BIT(CIF_FPU)
 #define _CIF_ENABLED_WAIT      BIT(CIF_ENABLED_WAIT)
 #define _CIF_MCCK_GUEST                BIT(CIF_MCCK_GUEST)
 #define _CIF_DEDICATED_CPU     BIT(CIF_DEDICATED_CPU)

diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index a674c7d25da5a1790367ea238d7b4c5b11327639..e3f70b94a79b3b042a66679a7a005987c0171ca1 100644 (file)
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -69,6 +69,7 @@ void arch_setup_new_exec(void);
 #define TIF_PATCH_PENDING      5       /* pending live patching update */
 #define TIF_PGSTE              6       /* New mm's will use 4K page tables */
 #define TIF_NOTIFY_SIGNAL      7       /* signal notifications exist */
+#define TIF_FPU                        8       /* restore FPU registers on exit to usermode */
 #define TIF_ISOLATE_BP_GUEST   9       /* Run KVM guests with isolated BP */
 #define TIF_PER_TRAP           10      /* Need to handle PER trap on exit to usermode */
 
@@ -92,6 +93,7 @@ void arch_setup_new_exec(void);
 #define _TIF_UPROBE            BIT(TIF_UPROBE)
 #define _TIF_GUARDED_STORAGE   BIT(TIF_GUARDED_STORAGE)
 #define _TIF_PATCH_PENDING     BIT(TIF_PATCH_PENDING)
+#define _TIF_FPU               BIT(TIF_FPU)
 #define _TIF_ISOLATE_BP_GUEST  BIT(TIF_ISOLATE_BP_GUEST)
 #define _TIF_PER_TRAP          BIT(TIF_PER_TRAP)
 

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 01c3b2d2821df7adcb610c775fae0669e146c22f..00f2e1741501c102ad8ba667774e6ad42046499f 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -220,7 +220,7 @@ SYM_FUNC_START(__sie64a)
        oi      __SIE_PROG0C+3(%r14),1          # we are going into SIE now
        tm      __SIE_PROG20+3(%r14),3          # last exit...
        jnz     .Lsie_skip
-       TSTMSK  __LC_CPU_FLAGS,_CIF_FPU
+       TSTMSK  __SF_SIE_FLAGS(%r15),_TIF_FPU
        jo      .Lsie_skip                      # exit if fp/vx regs changed
        lg      %r14,__SF_SIE_CONTROL_PHYS(%r15)        # get sie block phys addr
        BPEXIT  __SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST

diff --git a/arch/s390/kernel/fpu.c b/arch/s390/kernel/fpu.c
index 0a31408a46f3a030848183f22ec0d655457a6c61..12d6e9d971048c49d32c6c4afa870f58560a9909 100644 (file)
--- a/arch/s390/kernel/fpu.c
+++ b/arch/s390/kernel/fpu.c
@@ -117,7 +117,7 @@ void __load_fpu_regs(void)
                load_vx_regs(regs);
        else
                load_fp_regs(regs);
-       clear_cpu_flag(CIF_FPU);
+       clear_thread_flag(TIF_FPU);
 }
 
 void load_fpu_regs(void)
@@ -136,7 +136,7 @@ void save_fpu_regs(void)
 
        local_irq_save(flags);
 
-       if (test_cpu_flag(CIF_FPU))
+       if (test_thread_flag(TIF_FPU))
                goto out;
 
        state = &current->thread.fpu;
@@ -147,7 +147,7 @@ void save_fpu_regs(void)
                save_vx_regs(regs);
        else
                save_fp_regs(regs);
-       set_cpu_flag(CIF_FPU);
+       set_thread_flag(TIF_FPU);
 out:
        local_irq_restore(flags);
 }

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index b0578ea230e7348d8ec891f46db83188feef2d95..f4c355f080f2e4cc7330a7d8f60d1b6c5cb5186a 100644 (file)
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -88,7 +88,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
        /*
         * Save the floating-point or vector register state of the current
-        * task and set the CIF_FPU flag to lazy restore the FPU register
+        * task and set the TIF_FPU flag to lazy restore the FPU register
         * state when returning to user space.
         */
        save_fpu_regs();
@@ -196,11 +196,6 @@ void execve_tail(void)
 
 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
 {
-       /*
-        * save_fpu_regs() sets the CIF_FPU flag, which enforces
-        * a restore of the floating point / vector registers as
-        * soon as the next task returns to user space.
-        */
        save_fpu_regs();
        save_access_regs(&prev->thread.acrs[0]);
        save_ri_cb(prev->thread.ri_cb);

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8f44145397567bb653750c0f97791edab3c00cd7..0cee7192a1c2324f9837dda01c48584ded7a0fe4 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4829,7 +4829,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
                               vcpu->run->s.regs.gprs,
                               sizeof(sie_page->pv_grregs));
                }
-               if (test_cpu_flag(CIF_FPU))
+               if (test_thread_flag(TIF_FPU))
                        load_fpu_regs();
                exit_reason = sie64a(vcpu->arch.sie_block,
                                     vcpu->run->s.regs.gprs);

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 457d92c2949ab7f838d4fa8d4ef945e474358263..b8a242360ed04c8142499af6e6c1d95d5c7288af 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -1149,7 +1149,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
         */
        vcpu->arch.sie_block->prog0c |= PROG_IN_SIE;
        barrier();
-       if (test_cpu_flag(CIF_FPU))
+       if (test_thread_flag(TIF_FPU))
                load_fpu_regs();
        if (!kvm_s390_vcpu_sie_inhibited(vcpu))
                rc = sie64a(scb_s, vcpu->run->s.regs.gprs);