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KVM: arm64: pkvm: Remove struct cpu_sve_state

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There's no need for struct cpu_sve_state. Code would be simpler and more
robust without it, and removing it will simplify further cleanups (e.g.
adding an opaque type for the sve register state).

Protected KVM stores most of the host's system register state in
kvm_host_data::host_ctxt, which is an instance of struct
kvm_cpu_context. As kvm_cpu_context::sys_regs[] has a slot for ZCR_EL1,
we can store the host's ZCR_EL1 there.

While kvm_cpu_context::sys_regs doesn't have slots for FPSR and FPCR,
these are usually expected to be stored in struct user_fpsimd_state.
For historical reasons, __sve_save_state and __sve_restore_state()
expect a pointer to fpsr *within* struct user_fpsimd_state, assuming the
fpcr will immediately follow, as per the order within struct
user_fpsimd_state. We currently match this ordering in struct
cpu_sve_state, but it would be simpler and more robust to use struct
user_fpsimd_state directly.

After moving ZCR_EL1, FPSR, and FPCR out of struct cpu_sve_state, all
that's left is sve_regs, which can be represented as a pointer without
need for a container struct. This is kept as a pointer to u8 (matching
the array type), as this permits the compiler to catch unbalanced
referencing/dereferencing, which is not possible for pointers to void.

Apply the above changes, and remove cpu_sve_state.

I've dropped the comment regarding buffer alignment as AFAICT this was
never necessary. The LDR/STR (vector) instructions only require this
alignment when SCTLR_ELx.A==1, which is not the case for the kernel or
hyp code. Nothing else depends on the alignment.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
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: Mark Brown <broonie@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Rutland 2026-06-03 12:06:16 +01:00 committed by Will Deacon
parent da20bb4bc5
commit afd7af2b56
6 changed files with 23 additions and 36 deletions
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18
arch/arm64/include/asm/kvm_host.h
View File

@ -735,20 +735,6 @@ struct kvm_cpu_context {
u64 *vncr_array;
};
struct cpu_sve_state {
__u64 zcr_el1;
/*
* Ordering is important since __sve_save_state/__sve_restore_state
* relies on it.
*/
__u32 fpsr;
__u32 fpcr;
/* Must be SVE_VQ_BYTES (128 bit) aligned. */
__u8 sve_regs[];
};
/*
* This structure is instantiated on a per-CPU basis, and contains
* data that is:
@ -774,9 +760,9 @@ struct kvm_host_data {
/*
* Hyp VA.
* sve_state is only used in pKVM and if system_supports_sve().
* sve_regs is only used in pKVM and if system_supports_sve().
*/
struct cpu_sve_state *sve_state;
u8 *sve_regs;
/* Ownership of the FP regs */
enum {

3
arch/arm64/include/asm/kvm_pkvm.h
View File

@ -188,8 +188,7 @@ static inline size_t pkvm_host_sve_state_size(void)
if (!system_supports_sve())
return 0;
return size_add(sizeof(struct cpu_sve_state),
SVE_SIG_REGS_SIZE(sve_vq_from_vl(kvm_host_sve_max_vl)));
return SVE_SIG_REGS_SIZE(sve_vq_from_vl(kvm_host_sve_max_vl));
}
struct pkvm_mapping {

16
arch/arm64/kvm/arm.c
View File

@ -2495,10 +2495,10 @@ static void __init teardown_hyp_mode(void)
continue;
if (free_sve) {
struct cpu_sve_state *sve_state;
u8 *sve_regs;
sve_state = per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state;
free_pages((unsigned long) sve_state, pkvm_host_sve_state_order());
sve_regs = per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_regs;
free_pages((unsigned long) sve_regs, pkvm_host_sve_state_order());
}
free_pages(kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu], nvhe_percpu_order());
@ -2623,7 +2623,7 @@ static int init_pkvm_host_sve_state(void)
if (!page)
return -ENOMEM;
per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state = page_address(page);
per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_regs = page_address(page);
}
/*
@ -2644,11 +2644,11 @@ static void finalize_init_hyp_mode(void)
if (system_supports_sve() && is_protected_kvm_enabled()) {
for_each_possible_cpu(cpu) {
struct cpu_sve_state *sve_state;
u8 *sve_regs;
sve_state = per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state;
per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state =
kern_hyp_va(sve_state);
sve_regs = per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_regs;
per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_regs =
kern_hyp_va(sve_regs);
}
}
}

9
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -484,12 +484,13 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
static inline void __hyp_sve_save_host(void)
{
struct cpu_sve_state *sve_state = *host_data_ptr(sve_state);
struct kvm_cpu_context *hctxt = host_data_ptr(host_ctxt);
u8 *sve_regs = *host_data_ptr(sve_regs);
sve_state->zcr_el1 = read_sysreg_el1(SYS_ZCR);
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_state->sve_regs + sve_ffr_offset(kvm_host_sve_max_vl),
&sve_state->fpsr,
__sve_save_state(sve_regs + sve_ffr_offset(kvm_host_sve_max_vl),
&hctxt->fp_regs.fpsr,
true);
}

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

@ -41,7 +41,8 @@ static void __hyp_sve_save_guest(struct kvm_vcpu *vcpu)
static void __hyp_sve_restore_host(void)
{
struct cpu_sve_state *sve_state = *host_data_ptr(sve_state);
struct kvm_cpu_context *hctxt = host_data_ptr(host_ctxt);
u8 *sve_regs = *host_data_ptr(sve_regs);
/*
* On saving/restoring host sve state, always use the maximum VL for
@ -53,10 +54,10 @@ static void __hyp_sve_restore_host(void)
* need to be revisited.
*/
write_sysreg_s(sve_vq_from_vl(kvm_host_sve_max_vl) - 1, SYS_ZCR_EL2);
__sve_restore_state(sve_state->sve_regs + sve_ffr_offset(kvm_host_sve_max_vl),
&sve_state->fpsr,
__sve_restore_state(sve_regs + sve_ffr_offset(kvm_host_sve_max_vl),
&hctxt->fp_regs.fpsr,
true);
write_sysreg_el1(sve_state->zcr_el1, SYS_ZCR);
write_sysreg_el1(ctxt_sys_reg(hctxt, ZCR_EL1), SYS_ZCR);
}
static void fpsimd_sve_flush(void)

4
arch/arm64/kvm/hyp/nvhe/setup.c
View File

@ -82,9 +82,9 @@ static int pkvm_create_host_sve_mappings(void)
for (i = 0; i < hyp_nr_cpus; i++) {
struct kvm_host_data *host_data = per_cpu_ptr(&kvm_host_data, i);
struct cpu_sve_state *sve_state = host_data->sve_state;
u8 *sve_regs = host_data->sve_regs;
start = kern_hyp_va(sve_state);
start = kern_hyp_va(sve_regs);
end = start + PAGE_ALIGN(pkvm_host_sve_state_size());
ret = pkvm_create_mappings(start, end, PAGE_HYP);
if (ret)