arm64/sve: Explicitly load vector length when restoring SVE state

Currently when restoring the SVE state we supply the SVE vector length
as an argument to sve_load_state() and the underlying macros. This becomes
inconvenient with the addition of SME since we may need to restore any
combination of SVE and SME vector lengths, and we already separately
restore the vector length in the KVM code. We don't need to know the vector
length during the actual register load since the SME load instructions can
index into the data array for us.

Refactor the interface so we explicitly set the vector length separately
to restoring the SVE registers in preparation for adding SME support, no
functional change should be involved.

Signed-off-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: broonie

arch/arm64/include/asm/fpsimd.h

@@ -67,7 +67,7 @@ static inline void *sve_pffr(struct thread_struct *thread)
 
 extern void sve_save_state(void *state, u32 *pfpsr, int save_ffr);
 extern void sve_load_state(void const *state, u32 const *pfpsr,
-			   int restore_ffr, unsigned long vq_minus_1);
+			   int restore_ffr);
 extern void sve_flush_live(bool flush_ffr, unsigned long vq_minus_1);
 extern unsigned int sve_get_vl(void);
 extern void sve_set_vq(unsigned long vq_minus_1);

arch/arm64/include/asm/fpsimdmacros.h

@@ -241,7 +241,7 @@
 		str		w\nxtmp, [\xpfpsr, #4]
 .endm
 
-.macro __sve_load nxbase, xpfpsr, restore_ffr, nxtmp
+.macro sve_load nxbase, xpfpsr, restore_ffr, nxtmp
  _for n, 0, 31,	_sve_ldr_v	\n, \nxbase, \n - 34
 		cbz		\restore_ffr, 921f
 		_sve_ldr_p	0, \nxbase
@@ -254,8 +254,3 @@
 		ldr		w\nxtmp, [\xpfpsr, #4]
 		msr		fpcr, x\nxtmp
 .endm
-
-.macro sve_load nxbase, xpfpsr, restore_ffr, xvqminus1, nxtmp, xtmp2
-		sve_load_vq	\xvqminus1, x\nxtmp, \xtmp2
-		__sve_load	\nxbase, \xpfpsr, \restore_ffr, \nxtmp
-.endm

arch/arm64/kernel/entry-fpsimd.S

@@ -51,10 +51,9 @@ SYM_FUNC_END(sve_save_state)
  * x0 - pointer to buffer for state
  * x1 - pointer to storage for FPSR
  * x2 - Restore FFR if non-zero
- * x3 - VQ-1
  */
 SYM_FUNC_START(sve_load_state)
-	sve_load 0, x1, x2, x3, 4, x5
+	sve_load 0, x1, x2, 4
 	ret
 SYM_FUNC_END(sve_load_state)
 

arch/arm64/kernel/fpsimd.c

@@ -318,12 +318,13 @@ static void task_fpsimd_load(void)
 	WARN_ON(!system_supports_fpsimd());
 	WARN_ON(!have_cpu_fpsimd_context());
 
-	if (IS_ENABLED(CONFIG_ARM64_SVE) && test_thread_flag(TIF_SVE))
+	if (IS_ENABLED(CONFIG_ARM64_SVE) && test_thread_flag(TIF_SVE)) {
+		sve_set_vq(sve_vq_from_vl(task_get_sve_vl(current)) - 1);
 		sve_load_state(sve_pffr(&current->thread),
-			       &current->thread.uw.fpsimd_state.fpsr, true,
-			       sve_vq_from_vl(task_get_sve_vl(current)) - 1);
-	else
+			       &current->thread.uw.fpsimd_state.fpsr, true);
+	} else {
 		fpsimd_load_state(&current->thread.uw.fpsimd_state);
+	}
 }
 
 /*
@@ -1423,10 +1424,10 @@ void __efi_fpsimd_end(void)
 		    likely(__this_cpu_read(efi_sve_state_used))) {
 			char const *sve_state = this_cpu_ptr(efi_sve_state);
 
+			sve_set_vq(sve_vq_from_vl(sve_get_vl()) - 1);
 			sve_load_state(sve_state + sve_ffr_offset(sve_max_vl()),
 				       &this_cpu_ptr(&efi_fpsimd_state)->fpsr,
-				       true,
-				       sve_vq_from_vl(sve_get_vl()) - 1);
+				       true);
 
 			__this_cpu_write(efi_sve_state_used, false);
 		} else {

arch/arm64/kvm/hyp/fpsimd.S

@@ -22,7 +22,7 @@ SYM_FUNC_END(__fpsimd_restore_state)
 
 SYM_FUNC_START(__sve_restore_state)
 	mov	x2, #1
-	__sve_load 0, x1, x2, 3
+	sve_load 0, x1, x2, 3
 	ret
 SYM_FUNC_END(__sve_restore_state)