arm64: fpsimd: Split FPSR/FPCR from SVE save/restore

Regardless of whether the vector registers are saved in FPSIMD or SVE
format, we store FPSR and FPCR in user_fpsimd_state::{fpsr,fpcr}.

For historical reasons, the functions which save/restore SVE context
take a pointer to user_fpsimd_state::fpsr, and use this to access both
user_fpsimd_state::fpsr and user_fpsimd_state::fpcr. This is
unnecessarily fragile.

Move the save/restore of FPSR and FPCR into separate helper functions
which take a pointer to user_fpsimd_state. I've used read_sysreg_s() and
write_sysreg_s() as contemporary versions of LLVM will refuse to
directly assemble accesses to FPCR or FPSR unless the "fp" arch
extension is enabled.

For the moment, fpsimd_save_state() and fpsimd_load_state() are left
as-is with their own logic to save/restore FPSR and FPCR. This will be
unified in subsequent patches.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 36cf528e64971369523a8f70881df23c0a92307f..6fd5cdf5e5f1780f39db2ae1d97ec31d7a4a8629 100644 (file)
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -74,6 +74,18 @@ static inline void cpacr_restore(unsigned long cpacr)
 
 struct task_struct;
 
+static inline void fpsimd_save_common(struct user_fpsimd_state *state)
+{
+       state->fpsr = read_sysreg_s(SYS_FPSR);
+       state->fpcr = read_sysreg_s(SYS_FPCR);
+}
+
+static inline void fpsimd_load_common(const struct user_fpsimd_state *state)
+{
+       write_sysreg_s(state->fpsr, SYS_FPSR);
+       write_sysreg_s(state->fpcr, SYS_FPCR);
+}
+
 extern void fpsimd_save_state(struct user_fpsimd_state *state);
 extern void fpsimd_load_state(struct user_fpsimd_state *state);
 
@@ -157,9 +169,8 @@ static inline unsigned int sve_get_vl(void)
        return vl;
 }
 
-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);
+extern void sve_save_state(void *state, int save_ffr);
+extern void sve_load_state(void const *state, int restore_ffr);
 extern void sve_flush_live(bool flush_ffr, unsigned long vq_minus_1);
 extern void sme_save_state(void *state, int zt);
 extern void sme_load_state(void const *state, int zt);

diff --git a/arch/arm64/include/asm/fpsimdmacros.h b/arch/arm64/include/asm/fpsimdmacros.h
index c724fcad7ee0247a3866feebe2ec88b09a229f5e..1f32e0967dcd3a7a1bb6792fdb2f98e1d6324ff3 100644 (file)
--- a/arch/arm64/include/asm/fpsimdmacros.h
+++ b/arch/arm64/include/asm/fpsimdmacros.h
@@ -236,7 +236,7 @@
                _sve_wrffr      0
 .endm
 
-.macro sve_save nxbase, xpfpsr, save_ffr, nxtmp
+.macro sve_save nxbase, save_ffr
  _for n, 0, 31,        _sve_str_v      \n, \nxbase, \n - 34
  _for n, 0, 15,        _sve_str_p      \n, \nxbase, \n - 16
                cbz             \save_ffr, 921f
@@ -247,24 +247,15 @@
 922:
                _sve_str_p      0, \nxbase
                _sve_ldr_p      0, \nxbase, -16
-               mrs             x\nxtmp, fpsr
-               str             w\nxtmp, [\xpfpsr]
-               mrs             x\nxtmp, fpcr
-               str             w\nxtmp, [\xpfpsr, #4]
 .endm
 
-.macro sve_load nxbase, xpfpsr, restore_ffr, nxtmp
+.macro sve_load nxbase, restore_ffr
  _for n, 0, 31,        _sve_ldr_v      \n, \nxbase, \n - 34
                cbz             \restore_ffr, 921f
                _sve_ldr_p      0, \nxbase
                _sve_wrffr      0
 921:
  _for n, 0, 15,        _sve_ldr_p      \n, \nxbase, \n - 16
-
-               ldr             w\nxtmp, [\xpfpsr]
-               msr             fpsr, x\nxtmp
-               ldr             w\nxtmp, [\xpfpsr, #4]
-               msr             fpcr, x\nxtmp
 .endm
 
 .macro sme_save_za nxbase, xvl, nw

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 8d06b62e7188cf08e27a47d2850d5a1ded0e045a..0030cc1b52197032ae3b673f6d7029f778dc2519 100644 (file)
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -123,8 +123,8 @@ void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu);
 
 void __fpsimd_save_state(struct user_fpsimd_state *fp_regs);
 void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs);
-void __sve_save_state(void *sve_pffr, u32 *fpsr, int save_ffr);
-void __sve_restore_state(void *sve_pffr, u32 *fpsr, int restore_ffr);
+void __sve_save_state(void *sve, int save_ffr);
+void __sve_restore_state(void *sve, int restore_ffr);
 
 u64 __guest_enter(struct kvm_vcpu *vcpu);
 

diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S
index a124c6d3766cf8bdc38d729cbe00773ffec90eec..1a581597037cadcfd126a194001369d65b3bbd21 100644 (file)
--- a/arch/arm64/kernel/entry-fpsimd.S
+++ b/arch/arm64/kernel/entry-fpsimd.S
@@ -37,11 +37,10 @@ SYM_FUNC_END(fpsimd_load_state)
  * Save the SVE state
  *
  * x0 - pointer to buffer for state
- * x1 - pointer to storage for FPSR
- * w2 - Save FFR if non-zero
+ * w1 - Save FFR if non-zero
  */
 SYM_FUNC_START(sve_save_state)
-       sve_save 0, x1, w2, 3
+       sve_save 0, w1
        ret
 SYM_FUNC_END(sve_save_state)
 
@@ -49,11 +48,10 @@ SYM_FUNC_END(sve_save_state)
  * Load the SVE state
  *
  * x0 - pointer to buffer for state
- * x1 - pointer to storage for FPSR
- * w2 - Restore FFR if non-zero
+ * w1 - Restore FFR if non-zero
  */
 SYM_FUNC_START(sve_load_state)
-       sve_load 0, x1, w2, 4
+       sve_load 0, w1
        ret
 SYM_FUNC_END(sve_load_state)
 

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 2578c2372c89e13e9a2f54c1e92a8e2d12e1b28a..9806fea8fea7ccf4db363a40b4710157ad553ea9 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -426,8 +426,8 @@ static void task_fpsimd_load(void)
        if (restore_sve_regs) {
                WARN_ON_ONCE(current->thread.fp_type != FP_STATE_SVE);
                sve_load_state(sve_pffr(&current->thread),
-                              &current->thread.uw.fpsimd_state.fpsr,
                               restore_ffr);
+               fpsimd_load_common(&current->thread.uw.fpsimd_state);
        } else {
                WARN_ON_ONCE(current->thread.fp_type != FP_STATE_FPSIMD);
                fpsimd_load_state(&current->thread.uw.fpsimd_state);
@@ -509,7 +509,8 @@ static void fpsimd_save_user_state(void)
 
                sve_save_state((char *)last->sve_state +
                                        sve_ffr_offset(vl),
-                              &last->st->fpsr, save_ffr);
+                              save_ffr);
+               fpsimd_save_common(last->st);
                *last->fp_type = FP_STATE_SVE;
        } else {
                fpsimd_save_state(last->st);

diff --git a/arch/arm64/kvm/hyp/fpsimd.S b/arch/arm64/kvm/hyp/fpsimd.S
index 30507c50942ebf0bbc562bf6254665f79dd23b37..3d5b5e93ee5e05255ea120db8018e2abe59afea4 100644 (file)
--- a/arch/arm64/kvm/hyp/fpsimd.S
+++ b/arch/arm64/kvm/hyp/fpsimd.S
@@ -21,11 +21,11 @@ SYM_FUNC_START(__fpsimd_restore_state)
 SYM_FUNC_END(__fpsimd_restore_state)
 
 SYM_FUNC_START(__sve_restore_state)
-       sve_load 0, x1, w2, 3
+       sve_load 0, w1
        ret
 SYM_FUNC_END(__sve_restore_state)
 
 SYM_FUNC_START(__sve_save_state)
-       sve_save 0, x1, w2, 3
+       sve_save 0, w1
        ret
 SYM_FUNC_END(__sve_save_state)

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 6512dd3f75ae43f15de74c4cc23c2f00b2fbb4e3..eb76a863ebb84500a883c54a58bd53f5c3a484c8 100644 (file)
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -468,8 +468,8 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
         */
        sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2);
        __sve_restore_state(vcpu_sve_pffr(vcpu),
-                           &vcpu->arch.ctxt.fp_regs.fpsr,
                            true);
+       fpsimd_load_common(&vcpu->arch.ctxt.fp_regs);
 
        /*
         * The effective VL for a VM could differ from the max VL when running a
@@ -490,8 +490,8 @@ static inline void __hyp_sve_save_host(void)
        ctxt_sys_reg(hctxt, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
        write_sysreg_s(sve_vq_from_vl(kvm_host_sve_max_vl) - 1, SYS_ZCR_EL2);
        __sve_save_state(sve_regs + sve_ffr_offset(kvm_host_sve_max_vl),
-                        &hctxt->fp_regs.fpsr,
                         true);
+       fpsimd_save_common(&hctxt->fp_regs);
 }
 
 static inline void fpsimd_lazy_switch_to_guest(struct kvm_vcpu *vcpu)

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 31b0245a7e64db51d0ea513af115b959b1a2a527..2ed4720e4f70730a369c5eff28856db0baa83ca9 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -35,7 +35,8 @@ static void __hyp_sve_save_guest(struct kvm_vcpu *vcpu)
         * on the VL, so use a consistent (i.e., the maximum) guest VL.
         */
        sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2);
-       __sve_save_state(vcpu_sve_pffr(vcpu), &vcpu->arch.ctxt.fp_regs.fpsr, true);
+       __sve_save_state(vcpu_sve_pffr(vcpu), true);
+       fpsimd_save_common(&vcpu->arch.ctxt.fp_regs);
        write_sysreg_s(sve_vq_from_vl(kvm_host_sve_max_vl) - 1, SYS_ZCR_EL2);
 }
 
@@ -55,8 +56,8 @@ static void __hyp_sve_restore_host(void)
         */
        write_sysreg_s(sve_vq_from_vl(kvm_host_sve_max_vl) - 1, SYS_ZCR_EL2);
        __sve_restore_state(sve_regs + sve_ffr_offset(kvm_host_sve_max_vl),
-                           &hctxt->fp_regs.fpsr,
                            true);
+       fpsimd_load_common(&hctxt->fp_regs);
        write_sysreg_el1(ctxt_sys_reg(hctxt, ZCR_EL1), SYS_ZCR);
 }