| Message ID | 20250314-stable-sve-6-12-v1-3-ddc16609d9ba@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: arm64: Backport of SVE fixes to v6.12 | expand |
On Fri, Mar 14, 2025 at 12:35:15AM +0000, Mark Brown wrote: > From: Mark Rutland <mark.rutland@arm.com> > > 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> > --- What is the upstream git id for this on? thanks, greg k-h
On Fri, Mar 14, 2025 at 06:32:45AM +0100, Greg Kroah-Hartman wrote: > On Fri, Mar 14, 2025 at 12:35:15AM +0000, Mark Brown wrote: > > From: Mark Rutland <mark.rutland@arm.com> > > > > 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> > > --- > > What is the upstream git id for this on? It seems to be 8eca7f6d5100 ("KVM: arm64: Remove host FPSIMD saving for non-protected KVM").
On Fri, Mar 14, 2025 at 02:40:13PM +0000, Catalin Marinas wrote: > On Fri, Mar 14, 2025 at 06:32:45AM +0100, Greg Kroah-Hartman wrote: > > What is the upstream git id for this on? > It seems to be 8eca7f6d5100 ("KVM: arm64: Remove host FPSIMD saving for > non-protected KVM"). Yes, sorry.
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;