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KVM: arm64: Add save/restore support for FPMR

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Just like the rest of the FP/SIMD state, FPMR needs to be context
switched.

The only interesting thing here is that we need to treat the pKVM
part a bit differently, as the host FP state is never written back
to the vcpu thread, but instead stored locally and eagerly restored.

Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240820131802.3547589-5-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2024-08-20 14:17:58 +01:00
parent 7d9c1ed6f4
commit ef3be86021
6 changed files with 35 additions and 0 deletions
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10
arch/arm64/include/asm/kvm_host.h
View File

@ -599,6 +599,16 @@ struct kvm_host_data {
struct cpu_sve_state *sve_state;
};
union {
/* HYP VA pointer to the host storage for FPMR */
u64 *fpmr_ptr;
/*
* Used by pKVM only, as it needs to provide storage
* for the host
*/
u64 fpmr;
};
/* Ownership of the FP regs */
enum {
FP_STATE_FREE,

1
arch/arm64/kvm/fpsimd.c
View File

@ -63,6 +63,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
*/
*host_data_ptr(fp_owner) = FP_STATE_HOST_OWNED;
*host_data_ptr(fpsimd_state) = kern_hyp_va(&current->thread.uw.fpsimd_state);
*host_data_ptr(fpmr_ptr) = kern_hyp_va(&current->thread.uw.fpmr);
vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)

3
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -404,6 +404,9 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
else
__fpsimd_restore_state(&vcpu->arch.ctxt.fp_regs);
if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm)))
write_sysreg_s(__vcpu_sys_reg(vcpu, FPMR), SYS_FPMR);
/* Skip restoring fpexc32 for AArch64 guests */
if (!(read_sysreg(hcr_el2) & HCR_RW))
write_sysreg(__vcpu_sys_reg(vcpu, FPEXC32_EL2), fpexc32_el2);

9
arch/arm64/kvm/hyp/nvhe/hyp-main.c
View File

@ -62,6 +62,8 @@ static void fpsimd_sve_flush(void)
static void fpsimd_sve_sync(struct kvm_vcpu *vcpu)
{
bool has_fpmr;
if (!guest_owns_fp_regs())
return;
@ -73,11 +75,18 @@ static void fpsimd_sve_sync(struct kvm_vcpu *vcpu)
else
__fpsimd_save_state(&vcpu->arch.ctxt.fp_regs);
has_fpmr = kvm_has_fpmr(kern_hyp_va(vcpu->kvm));
if (has_fpmr)
__vcpu_sys_reg(vcpu, FPMR) = read_sysreg_s(SYS_FPMR);
if (system_supports_sve())
__hyp_sve_restore_host();
else
__fpsimd_restore_state(*host_data_ptr(fpsimd_state));
if (has_fpmr)
write_sysreg_s(*host_data_ptr(fpmr), SYS_FPMR);
*host_data_ptr(fp_owner) = FP_STATE_HOST_OWNED;
}

9
arch/arm64/kvm/hyp/nvhe/switch.c
View File

@ -198,6 +198,15 @@ static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
} else {
__fpsimd_save_state(*host_data_ptr(fpsimd_state));
}
if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm))) {
u64 val = read_sysreg_s(SYS_FPMR);
if (unlikely(is_protected_kvm_enabled()))
*host_data_ptr(fpmr) = val;
else
**host_data_ptr(fpmr_ptr) = val;
}
}
static const exit_handler_fn hyp_exit_handlers[] = {

3
arch/arm64/kvm/hyp/vhe/switch.c
View File

@ -312,6 +312,9 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code)
static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
{
__fpsimd_save_state(*host_data_ptr(fpsimd_state));
if (kvm_has_fpmr(vcpu->kvm))
**host_data_ptr(fpmr_ptr) = read_sysreg_s(SYS_FPMR);
}
static bool kvm_hyp_handle_tlbi_el2(struct kvm_vcpu *vcpu, u64 *exit_code)