On Fri, Mar 21, 2025 at 12:12:59AM +0000, Mark Brown wrote:
From: Mark Rutland mark.rutland@arm.com
[ Upstream commit 8eca7f6d5100b6997df4f532090bc3f7e0203bef ]
Now that the host eagerly saves its own FPSIMD/SVE/SME state, non-protected KVM never needs to save the host FPSIMD/SVE/SME state, and the code to do this is never used. Protected KVM still needs to save/restore the host FPSIMD/SVE state to avoid leaking guest state to the host (and to avoid revealing to the host whether the guest used FPSIMD/SVE/SME), and that code needs to be retained.
Remove the unused code and data structures.
To avoid the need for a stub copy of kvm_hyp_save_fpsimd_host() in the VHE hyp code, the nVHE/hVHE version is moved into the shared switch header, where it is only invoked when KVM is in protected mode.
Signed-off-by: Mark Rutland mark.rutland@arm.com Reviewed-by: Mark Brown broonie@kernel.org Tested-by: Mark Brown broonie@kernel.org Acked-by: Will Deacon will@kernel.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Fuad Tabba tabba@google.com Cc: Marc Zyngier maz@kernel.org Cc: Oliver Upton oliver.upton@linux.dev Reviewed-by: Oliver Upton oliver.upton@linux.dev Link: https://lore.kernel.org/r/20250210195226.1215254-3-mark.rutland@arm.com Signed-off-by: Marc Zyngier maz@kernel.org Signed-off-by: Mark Brown broonie@kernel.org
arch/arm64/include/asm/kvm_host.h | 20 +++++--------------- arch/arm64/kvm/arm.c | 8 -------- arch/arm64/kvm/fpsimd.c | 2 -- arch/arm64/kvm/hyp/include/hyp/switch.h | 25 +++++++++++++++++++++++-- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 +- arch/arm64/kvm/hyp/nvhe/switch.c | 28 ---------------------------- arch/arm64/kvm/hyp/vhe/switch.c | 8 -------- 7 files changed, 29 insertions(+), 64 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index d148cf578cb84e7dec4d1add2afa60a3c7a1e041..d8802490b25cba65369f03d94627a2624f14b072 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -602,23 +602,13 @@ struct kvm_host_data { struct kvm_cpu_context host_ctxt; /*
* All pointers in this union are hyp VA.
* Hyp VA.*/
- sve_state is only used in pKVM and if system_supports_sve().
- union {
struct user_fpsimd_state *fpsimd_state;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;- };
- struct cpu_sve_state *sve_state;
- /* Used by pKVM only. */
- u64 fpmr;
/* Ownership of the FP regs */ enum { diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index e6f0443210a8b7a65f616b25b2e6f74a05683ed6..634d3f62481827a3bf3aba6bf78cafed71b5bd32 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2476,14 +2476,6 @@ static void finalize_init_hyp_mode(void) per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state = kern_hyp_va(sve_state); }
- } else {
for_each_possible_cpu(cpu) {struct user_fpsimd_state *fpsimd_state;fpsimd_state = &per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->host_ctxt.fp_regs;per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->fpsimd_state =kern_hyp_va(fpsimd_state);}} diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index efb54ed60fe1d1d8a904b10a4a4bd3c820d9dac5..2ee6bde85235581d6bc9cba7e578c55875b5d5a1 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -64,8 +64,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) */ fpsimd_save_and_flush_cpu_state(); *host_data_ptr(fp_owner) = FP_STATE_FREE;
- *host_data_ptr(fpsimd_state) = NULL;
- *host_data_ptr(fpmr_ptr) = NULL;
vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index 5310fe1da6165bcdedfb5ce61bce353e4c9dd58b..a7f6a653f33718d1a25e232608e63ea287f2a672 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -344,7 +344,28 @@ static inline void __hyp_sve_save_host(void) true); } -static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu); +static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) +{
- /*
* Non-protected kvm relies on the host restoring its sve state.* Protected kvm restores the host's sve state as not to reveal that* fpsimd was used by a guest nor leak upper sve bits.*/- if (system_supports_sve()) {
__hyp_sve_save_host();/* Re-enable SVE traps if not supported for the guest vcpu. */if (!vcpu_has_sve(vcpu))cpacr_clear_set(CPACR_ELx_ZEN, 0);- } else {
__fpsimd_save_state(host_data_ptr(host_ctxt.fp_regs));- }
- if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm)))
*host_data_ptr(fpmr) = read_sysreg_s(SYS_FPMR);+}
/*
- We trap the first access to the FP/SIMD to save the host context and
@@ -394,7 +415,7 @@ 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 (host_owns_fp_regs())
- if (is_protected_kvm_enabled() && host_owns_fp_regs()) kvm_hyp_save_fpsimd_host(vcpu);
/* Restore the guest state */ diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index fefc89209f9e41c95478f6770881eb314a38b4c2..4e757a77322c9efc59cdff501745f7c80d452358 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -83,7 +83,7 @@ static void fpsimd_sve_sync(struct kvm_vcpu *vcpu) if (system_supports_sve()) __hyp_sve_restore_host(); else
__fpsimd_restore_state(*host_data_ptr(fpsimd_state));
__fpsimd_restore_state(host_data_ptr(host_ctxt.fp_regs));if (has_fpmr) write_sysreg_s(*host_data_ptr(fpmr), SYS_FPMR); diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index 81d933a71310fd1132b2450cd08108e071a2cf78..3ce16f90fe6af7be21bc7b84a9d8b3905b8b08a7 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -193,34 +193,6 @@ static bool kvm_handle_pvm_sys64(struct kvm_vcpu *vcpu, u64 *exit_code) kvm_handle_pvm_sysreg(vcpu, exit_code)); } -static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) -{
- /*
* Non-protected kvm relies on the host restoring its sve state.* Protected kvm restores the host's sve state as not to reveal that* fpsimd was used by a guest nor leak upper sve bits.*/- if (unlikely(is_protected_kvm_enabled() && system_supports_sve())) {
__hyp_sve_save_host();/* Re-enable SVE traps if not supported for the guest vcpu. */if (!vcpu_has_sve(vcpu))cpacr_clear_set(CPACR_ELx_ZEN, 0);- } 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[] = { [0 ... ESR_ELx_EC_MAX] = NULL, [ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32, diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 80581b1c399595fd64d0ccada498edac322480a6..e7ca0424107adec2371ae4553ebab9857c60b6d9 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -309,14 +309,6 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) return true; } -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) { int ret = -EINVAL;
-- 2.39.5