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KVM: arm64: Rework SVE host-save/guest-restore

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In order to keep the code readable, move the host-save/guest-restore
sequences in their own functions, with the following changes:
- the hypervisor ZCR is now set from C code
- ZCR_EL2 is always used as the EL2 accessor

This results in some minor assembler macro rework.
No functional change intended.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2021-03-16 08:52:40 +00:00
parent 71ce1ae56e
commit 52029198c1
4 changed files with 32 additions and 20 deletions
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8
arch/arm64/include/asm/fpsimdmacros.h
View File

@ -232,8 +232,7 @@
str w\nxtmp, [\xpfpsr, #4]
.endm
.macro sve_load nxbase, xpfpsr, xvqminus1, nxtmp, xtmp2
sve_load_vq \xvqminus1, x\nxtmp, \xtmp2
.macro __sve_load nxbase, xpfpsr, nxtmp
_for n, 0, 31, _sve_ldr_v \n, \nxbase, \n - 34
_sve_ldr_p 0, \nxbase
_sve_wrffr 0
@ -244,3 +243,8 @@
ldr w\nxtmp, [\xpfpsr, #4]
msr fpcr, x\nxtmp
.endm
.macro sve_load nxbase, xpfpsr, xvqminus1, nxtmp, xtmp2
sve_load_vq \xvqminus1, x\nxtmp, \xtmp2
__sve_load \nxbase, \xpfpsr, \nxtmp
.endm

2
arch/arm64/include/asm/kvm_hyp.h
View File

@ -86,7 +86,7 @@ void __debug_switch_to_host(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);
void __sve_restore_state(void *sve_pffr, u32 *fpsr, unsigned int vqminus1);
void __sve_restore_state(void *sve_pffr, u32 *fpsr);
#ifndef __KVM_NVHE_HYPERVISOR__
void activate_traps_vhe_load(struct kvm_vcpu *vcpu);

2
arch/arm64/kvm/hyp/fpsimd.S
View File

@ -21,7 +21,7 @@ SYM_FUNC_START(__fpsimd_restore_state)
SYM_FUNC_END(__fpsimd_restore_state)
SYM_FUNC_START(__sve_restore_state)
sve_load 0, x1, x2, 3, x4
__sve_load 0, x1, 2
ret
SYM_FUNC_END(__sve_restore_state)

40
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -196,6 +196,24 @@ static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
return true;
}
static inline void __hyp_sve_save_host(struct kvm_vcpu *vcpu)
{
struct thread_struct *thread;
thread = container_of(vcpu->arch.host_fpsimd_state, struct thread_struct,
uw.fpsimd_state);
__sve_save_state(sve_pffr(thread), &vcpu->arch.host_fpsimd_state->fpsr);
}
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);
write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
}
/* Check for an FPSIMD/SVE trap and handle as appropriate */
static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
{
@ -251,28 +269,18 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
* In the SVE case, VHE is assumed: it is enforced by
* Kconfig and kvm_arch_init().
*/
if (sve_host) {
struct thread_struct *thread = container_of(
vcpu->arch.host_fpsimd_state,
struct thread_struct, uw.fpsimd_state);
__sve_save_state(sve_pffr(thread),
&vcpu->arch.host_fpsimd_state->fpsr);
} else {
if (sve_host)
__hyp_sve_save_host(vcpu);
else
__fpsimd_save_state(vcpu->arch.host_fpsimd_state);
}
vcpu->arch.flags &= ~KVM_ARM64_FP_HOST;
}
if (sve_guest) {
__sve_restore_state(vcpu_sve_pffr(vcpu),
&vcpu->arch.ctxt.fp_regs.fpsr,
vcpu_sve_vq(vcpu) - 1);
write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
} else {
if (sve_guest)
__hyp_sve_restore_guest(vcpu);
else
__fpsimd_restore_state(&vcpu->arch.ctxt.fp_regs);
}
/* Skip restoring fpexc32 for AArch64 guests */
if (!(read_sysreg(hcr_el2) & HCR_RW))