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KVM: arm64: Exclude FP ownership from kvm_vcpu_arch

Browse source 
In retrospect, it is fairly obvious that the FP state ownership
is only meaningful for a given CPU, and that locating this
information in the vcpu was just a mistake.

Move the ownership tracking into the host data structure, and
rename it from fp_state to fp_owner, which is a better description
(name suggested by Mark Brown).

Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2024-03-01 17:42:31 +00:00
parent 51e09b5572
commit 5294afdbf4
8 changed files with 19 additions and 27 deletions
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4
arch/arm64/include/asm/kvm_emulate.h
View file

@ -588,7 +588,7 @@ static __always_inline u64 kvm_get_reset_cptr_el2(struct kvm_vcpu *vcpu)
val = (CPACR_EL1_FPEN_EL0EN | CPACR_EL1_FPEN_EL1EN);
if (!vcpu_has_sve(vcpu) ||
(vcpu->arch.fp_state != FP_STATE_GUEST_OWNED))
(*host_data_ptr(fp_owner) != FP_STATE_GUEST_OWNED))
val |= CPACR_EL1_ZEN_EL1EN | CPACR_EL1_ZEN_EL0EN;
if (cpus_have_final_cap(ARM64_SME))
val |= CPACR_EL1_SMEN_EL1EN | CPACR_EL1_SMEN_EL0EN;
@ -596,7 +596,7 @@ static __always_inline u64 kvm_get_reset_cptr_el2(struct kvm_vcpu *vcpu)
val = CPTR_NVHE_EL2_RES1;
if (vcpu_has_sve(vcpu) &&
(vcpu->arch.fp_state == FP_STATE_GUEST_OWNED))
(*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED))
val |= CPTR_EL2_TZ;
if (cpus_have_final_cap(ARM64_SME))
val &= ~CPTR_EL2_TSM;

14
arch/arm64/include/asm/kvm_host.h
View file

@ -545,6 +545,13 @@ struct kvm_host_data {
struct kvm_cpu_context host_ctxt;
struct user_fpsimd_state *fpsimd_state; /* hyp VA */
/* Ownership of the FP regs */
enum {
FP_STATE_FREE,
FP_STATE_HOST_OWNED,
FP_STATE_GUEST_OWNED,
} fp_owner;
/*
* host_debug_state contains the host registers which are
* saved and restored during world switches.
@ -622,13 +629,6 @@ struct kvm_vcpu_arch {
/* Exception Information */
struct kvm_vcpu_fault_info fault;
/* Ownership of the FP regs */
enum {
FP_STATE_FREE,
FP_STATE_HOST_OWNED,
FP_STATE_GUEST_OWNED,
} fp_state;
/* Configuration flags, set once and for all before the vcpu can run */
u8 cflags;

6
arch/arm64/kvm/arm.c
View file

@ -378,12 +378,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
/*
* Default value for the FP state, will be overloaded at load
* time if we support FP (pretty likely)
*/
vcpu->arch.fp_state = FP_STATE_FREE;
/* Set up the timer */
kvm_timer_vcpu_init(vcpu);

10
arch/arm64/kvm/fpsimd.c
View file

@ -84,7 +84,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
* guest in kvm_arch_vcpu_ctxflush_fp() and override this to
* FP_STATE_FREE if the flag set.
*/
vcpu->arch.fp_state = FP_STATE_HOST_OWNED;
*host_data_ptr(fp_owner) = FP_STATE_HOST_OWNED;
*host_data_ptr(fpsimd_state) = kern_hyp_va(&current->thread.uw.fpsimd_state);
vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
@ -109,7 +109,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
* been saved, this is very unlikely to happen.
*/
if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) {
vcpu->arch.fp_state = FP_STATE_FREE;
*host_data_ptr(fp_owner) = FP_STATE_FREE;
fpsimd_save_and_flush_cpu_state();
}
}
@ -125,7 +125,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu)
{
if (test_thread_flag(TIF_FOREIGN_FPSTATE))
vcpu->arch.fp_state = FP_STATE_FREE;
*host_data_ptr(fp_owner) = FP_STATE_FREE;
}
/*
@ -141,7 +141,7 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
WARN_ON_ONCE(!irqs_disabled());
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED) {
/*
* Currently we do not support SME guests so SVCR is
@ -195,7 +195,7 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
isb();
}
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED) {
if (vcpu_has_sve(vcpu)) {
__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);

6
arch/arm64/kvm/hyp/include/hyp/switch.h
View file

@ -42,7 +42,7 @@ extern struct kvm_exception_table_entry __stop___kvm_ex_table;
/* Check whether the FP regs are owned by the guest */
static inline bool guest_owns_fp_regs(struct kvm_vcpu *vcpu)
{
return vcpu->arch.fp_state == FP_STATE_GUEST_OWNED;
return *host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED;
}
/* Save the 32-bit only FPSIMD system register state */
@ -376,7 +376,7 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
isb();
/* Write out the host state if it's in the registers */
if (vcpu->arch.fp_state == FP_STATE_HOST_OWNED)
if (*host_data_ptr(fp_owner) == FP_STATE_HOST_OWNED)
__fpsimd_save_state(*host_data_ptr(fpsimd_state));
/* Restore the guest state */
@ -389,7 +389,7 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
if (!(read_sysreg(hcr_el2) & HCR_RW))
write_sysreg(__vcpu_sys_reg(vcpu, FPEXC32_EL2), fpexc32_el2);
vcpu->arch.fp_state = FP_STATE_GUEST_OWNED;
*host_data_ptr(fp_owner) = FP_STATE_GUEST_OWNED;
return true;
}

2
arch/arm64/kvm/hyp/nvhe/hyp-main.c
View file

@ -39,7 +39,6 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.cptr_el2 = host_vcpu->arch.cptr_el2;
hyp_vcpu->vcpu.arch.iflags = host_vcpu->arch.iflags;
hyp_vcpu->vcpu.arch.fp_state = host_vcpu->arch.fp_state;
hyp_vcpu->vcpu.arch.debug_ptr = kern_hyp_va(host_vcpu->arch.debug_ptr);
@ -63,7 +62,6 @@ static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
host_vcpu->arch.fault = hyp_vcpu->vcpu.arch.fault;
host_vcpu->arch.iflags = hyp_vcpu->vcpu.arch.iflags;
host_vcpu->arch.fp_state = hyp_vcpu->vcpu.arch.fp_state;
host_cpu_if->vgic_hcr = hyp_cpu_if->vgic_hcr;
for (i = 0; i < hyp_cpu_if->used_lrs; ++i)

2
arch/arm64/kvm/hyp/nvhe/switch.c
View file

@ -337,7 +337,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
__sysreg_restore_state_nvhe(host_ctxt);
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED)
if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED)
__fpsimd_save_fpexc32(vcpu);
__debug_switch_to_host(vcpu);

2
arch/arm64/kvm/hyp/vhe/switch.c
View file

@ -258,7 +258,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
sysreg_restore_host_state_vhe(host_ctxt);
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED)
if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED)
__fpsimd_save_fpexc32(vcpu);
__debug_switch_to_host(vcpu);