| Message ID | 20240613201756.3258227-2-oliver.upton@linux.dev (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: nv: FPSIMD/SVE, plus some other CPTR goodies | expand |
On Thu, 13 Jun 2024 21:17:42 +0100, Oliver Upton <oliver.upton@linux.dev> wrote: > > From: Jintack Lim <jintack.lim@linaro.org> > > Give precedence to the guest hypervisor's trap configuration when > routing an FP/ASIMD trap taken to EL2. Take advantage of the > infrastructure for translating CPTR_EL2 into the VHE (i.e. EL1) format > and base the trap decision solely on the VHE view of the register. The > in-memory value of CPTR_EL2 will always be up to date for the guest > hypervisor (more on that later), so just read it directly from memory. > > Bury all of this behind a macro keyed off of the CPTR bitfield in > anticipation of supporting other traps (e.g. SVE). > > Signed-off-by: Jintack Lim <jintack.lim@linaro.org> > Signed-off-by: Christoffer Dall <christoffer.dall@arm.com> > [maz: account for HCR_EL2.E2H when testing for TFP/FPEN, with > all the hard work actually being done by Chase Conklin] > Signed-off-by: Marc Zyngier <maz@kernel.org> > [ oliver: translate nVHE->VHE format for testing traps; macro for reuse > in other CPTR_EL2.xEN fields ] > Signed-off-by: Oliver Upton <oliver.upton@linux.dev> > --- > arch/arm64/include/asm/kvm_emulate.h | 43 +++++++++++++++++++++++++ > arch/arm64/include/asm/kvm_nested.h | 1 - > arch/arm64/kvm/handle_exit.c | 16 ++++++--- > arch/arm64/kvm/hyp/include/hyp/switch.h | 3 ++ > 4 files changed, 58 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index 501e3e019c93..c3c5a5999ed7 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -11,6 +11,7 @@ > #ifndef __ARM64_KVM_EMULATE_H__ > #define __ARM64_KVM_EMULATE_H__ > > +#include <linux/bitfield.h> > #include <linux/kvm_host.h> > > #include <asm/debug-monitors.h> > @@ -599,4 +600,46 @@ static __always_inline void kvm_reset_cptr_el2(struct kvm_vcpu *vcpu) > > kvm_write_cptr_el2(val); > } > + > +/* > + * Returns a 'sanitised' view of CPTR_EL2, translating from nVHE to the VHE > + * format if E2H isn't set. > + */ > +static inline u64 vcpu_sanitised_cptr_el2(const struct kvm_vcpu *vcpu) > +{ > + u64 cptr = __vcpu_sys_reg(vcpu, CPTR_EL2); > + > + if (!vcpu_el2_e2h_is_set(vcpu)) > + cptr = translate_cptr_el2_to_cpacr_el1(cptr); > + > + return cptr; > +} > + > +static inline bool ____cptr_xen_trap_enabled(const struct kvm_vcpu *vcpu, > + unsigned int xen) > +{ > + switch (xen) { > + case 0b00: > + case 0b10: > + return true; > + case 0b01: > + return vcpu_el2_tge_is_set(vcpu) && !vcpu_is_el2(vcpu); > + case 0b11: > + default: > + return false; > + } > +} > + > +#define __guest_hyp_cptr_xen_trap_enabled(vcpu, xen) \ > + (!vcpu_has_nv(vcpu) ? false : \ > + ____cptr_xen_trap_enabled(vcpu, \ > + SYS_FIELD_GET(CPACR_ELx, xen, \ > + vcpu_sanitised_cptr_el2(vcpu)))) > + > +static inline bool guest_hyp_fpsimd_traps_enabled(const struct kvm_vcpu *vcpu) > +{ > + return __guest_hyp_cptr_xen_trap_enabled(vcpu, FPEN); > +} > + > + > #endif /* __ARM64_KVM_EMULATE_H__ */ > diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h > index 5e0ab0596246..5d55f76254c3 100644 > --- a/arch/arm64/include/asm/kvm_nested.h > +++ b/arch/arm64/include/asm/kvm_nested.h > @@ -75,5 +75,4 @@ static inline bool kvm_auth_eretax(struct kvm_vcpu *vcpu, u64 *elr) > return false; > } > #endif > - > #endif /* __ARM64_KVM_NESTED_H */ nit: spurious change. Aside from that: Reviewed-by: Marc Zyngier <maz@kernel.org> M.
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index 501e3e019c93..c3c5a5999ed7 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -11,6 +11,7 @@ #ifndef __ARM64_KVM_EMULATE_H__ #define __ARM64_KVM_EMULATE_H__ +#include <linux/bitfield.h> #include <linux/kvm_host.h> #include <asm/debug-monitors.h> @@ -599,4 +600,46 @@ static __always_inline void kvm_reset_cptr_el2(struct kvm_vcpu *vcpu) kvm_write_cptr_el2(val); } + +/* + * Returns a 'sanitised' view of CPTR_EL2, translating from nVHE to the VHE + * format if E2H isn't set. + */ +static inline u64 vcpu_sanitised_cptr_el2(const struct kvm_vcpu *vcpu) +{ + u64 cptr = __vcpu_sys_reg(vcpu, CPTR_EL2); + + if (!vcpu_el2_e2h_is_set(vcpu)) + cptr = translate_cptr_el2_to_cpacr_el1(cptr); + + return cptr; +} + +static inline bool ____cptr_xen_trap_enabled(const struct kvm_vcpu *vcpu, + unsigned int xen) +{ + switch (xen) { + case 0b00: + case 0b10: + return true; + case 0b01: + return vcpu_el2_tge_is_set(vcpu) && !vcpu_is_el2(vcpu); + case 0b11: + default: + return false; + } +} + +#define __guest_hyp_cptr_xen_trap_enabled(vcpu, xen) \ + (!vcpu_has_nv(vcpu) ? false : \ + ____cptr_xen_trap_enabled(vcpu, \ + SYS_FIELD_GET(CPACR_ELx, xen, \ + vcpu_sanitised_cptr_el2(vcpu)))) + +static inline bool guest_hyp_fpsimd_traps_enabled(const struct kvm_vcpu *vcpu) +{ + return __guest_hyp_cptr_xen_trap_enabled(vcpu, FPEN); +} + + #endif /* __ARM64_KVM_EMULATE_H__ */ diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h index 5e0ab0596246..5d55f76254c3 100644 --- a/arch/arm64/include/asm/kvm_nested.h +++ b/arch/arm64/include/asm/kvm_nested.h @@ -75,5 +75,4 @@ static inline bool kvm_auth_eretax(struct kvm_vcpu *vcpu, u64 *elr) return false; } #endif - #endif /* __ARM64_KVM_NESTED_H */ diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index b037f0a0e27e..59fe9b10a87a 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -94,11 +94,19 @@ static int handle_smc(struct kvm_vcpu *vcpu) } /* - * Guest access to FP/ASIMD registers are routed to this handler only - * when the system doesn't support FP/ASIMD. + * This handles the cases where the system does not support FP/ASIMD or when + * we are running nested virtualization and the guest hypervisor is trapping + * FP/ASIMD accesses by its guest guest. + * + * All other handling of guest vs. host FP/ASIMD register state is handled in + * fixup_guest_exit(). */ -static int handle_no_fpsimd(struct kvm_vcpu *vcpu) +static int kvm_handle_fpasimd(struct kvm_vcpu *vcpu) { + if (guest_hyp_fpsimd_traps_enabled(vcpu)) + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu)); + + /* This is the case when the system doesn't support FP/ASIMD. */ kvm_inject_undefined(vcpu); return 1; } @@ -304,7 +312,7 @@ static exit_handle_fn arm_exit_handlers[] = { [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, - [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, + [ESR_ELx_EC_FP_ASIMD] = kvm_handle_fpasimd, [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, }; diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index a92566f36022..b302d32f8326 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -341,6 +341,9 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code) /* Only handle traps the vCPU can support here: */ switch (esr_ec) { case ESR_ELx_EC_FP_ASIMD: + /* Forward traps to the guest hypervisor as required */ + if (guest_hyp_fpsimd_traps_enabled(vcpu)) + return false; break; case ESR_ELx_EC_SVE: if (!sve_guest)