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Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v9 13/39] KVM: arm64: Manage GCS registers for guests In-Reply-To: <20240625-arm64-gcs-v9-13-0f634469b8f0@kernel.org> References: <20240625-arm64-gcs-v9-0-0f634469b8f0@kernel.org> <20240625-arm64-gcs-v9-13-0f634469b8f0@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.3 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: broonie@kernel.org, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, akpm@linux-foundation.org, oliver.upton@linux.dev, james.morse@arm.com, suzuki.poulose@arm.com, arnd@arndb.de, oleg@redhat.com, ebiederm@xmission.com, shuah@kernel.org, rick.p.edgecombe@intel.com, debug@rivosinc.com, ardb@kernel.org, Szabolcs.Nagy@arm.com, kees@kernel.org, hjl.tools@gmail.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, fweimer@redhat.com, brauner@kernel.org, thiago.bauermann@linaro.org, ross.burton@arm.com, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 399621A000A X-Stat-Signature: h6yzoqkad6bngcymffpci1oig1gyat8h X-Rspam-User: X-HE-Tag: 1720624652-270033 X-HE-Meta: U2FsdGVkX19kAudDvomXjgITRzE3wbUnWxUGi8gpITyL6pMR7+pTgK44G7ItDDHUCbdABjN+sN6SKXBlnYHgH8s1dIwR4ysk6VM9ItVO5rMc7eh7si+aPHai5wwkOiX7EaYgjmeCuotWRKA9W5m2CTD4qbK3pZC1Kjhn93CVxOzCtbNB0AvTv3CJZiGtt+WtOYC7hYC01d8aTz0oiALZmNTXX2PPMXr8F0jU+YxVK6Lr6fWVq9f6Ha6vDlLXli5pv5mwoIO7PTXyEEvmfBygeaGBQ3/oOmkhMoEYPAStlXhTIjt98epoWyPRw/KBu8wNaYEiyN/XdM3n8BKiy2Pc710o38QDZUACnbTlChw+wC+xcmTdDSGvmGS3oNJdXqWp/st05MuzdxI+vDZVo0ToXtquvAuASqcTmveqKQGNIJCZ/2kMIkSJKMxEQ4eMMyxLFCfJhD8w/NjGUovpBZzhAA0XZJ0GadRpE8WNoc2T1WdGb81cVnEniQUJf49Ro079g8OXicT7y+y+LNoxCwgr5iV24cEEliQiwRs2miXon27L2f+uT2nXs9c3dD74+eBUj8miRmAnLr5/NJdC55NGLOVuuupBTsXGjDa31ssJvyHQIJxAkGght5OE6IMSWleUs9gW+apyyT+vI+xWVyq2p9Bsa/5H9zluK1DTtUNrXivDGmCVVrnzpI3cnRae3xiinOmgJatMcAspN5uNrqjvYeopJtJEyxM3heR+JXxzdSlfaGsAQzghibLIT8D3+xJFLkJUUB8rwo3f/k/WOJKH6Q6ih+R00g1VjCnIdA7qHb3TEyJUP9M1NjQVe2hdWr/mSgOHpVe1BaLGOwGob7cOY2MPguuoP5bwnSNg4a1maf0qcqh9HK72k2WzXCJ8Jxciu8j/dyia1t8N3Q/hSIAp7NRkqpzJeLCPXd1JVq4aaJKHjO49VJU/Jyf3OU+yRzAG0d2kZS2gFJ/sMH0gEZJ A6NtWOeR hfDEj+S74vtDRiC51ep9f4lFrDBKduyXS2qBii6B+9GdtP0KvJF09G9I5Y4yFz/y//D0N7gqnS6PBKpqOvaCs42kJxIIHS4FRv6qrDZCmCwxfMy5hc0sikf2CYH6CwCsRFu7lVfRkwNT5ZgPUzMfQexIzvygw+wE7x32RVd9MBDrqwr04vfy6r395sFlUyvwEC7jqqZ4ERpQ79uFB5HfitEE5sbrpIAqRDOIsQ4/PcsvT2JdwpWvqoGjeRaq3XkQkICPrsym3WeSBPcbACAODCfZ5KXjPPoKCYpV5DJXwlkmyuOnTKe2pQ9sCfZ8yiWWEt4iQ9/hqp9C91l0irEFkW5ecjd0GU51Wsf4JRsKz3VN5sa8esRbYbRtg9NF/sdBRcfiv X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 25 Jun 2024 15:57:41 +0100, Mark Brown wrote: > > GCS introduces a number of system registers for EL1 and EL0, on systems > with GCS we need to context switch them and expose them to VMMs to allow > guests to use GCS, as well as describe their fine grained traps to > nested virtualisation. Traps are already disabled. I don't see anything related to FGTs at all. > > Reviewed-by: Thiago Jung Bauermann > Signed-off-by: Mark Brown > --- > arch/arm64/include/asm/kvm_host.h | 14 +++++++++ > arch/arm64/include/asm/vncr_mapping.h | 2 ++ > arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 48 +++++++++++++++++++++++------- > arch/arm64/kvm/sys_regs.c | 25 +++++++++++++++- > 4 files changed, 78 insertions(+), 11 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 36b8e97bf49e..316fb412f355 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -411,6 +411,10 @@ enum vcpu_sysreg { > GCR_EL1, /* Tag Control Register */ > TFSRE0_EL1, /* Tag Fault Status Register (EL0) */ > > + /* Guarded Control Stack registers */ > + GCSCRE0_EL1, /* Guarded Control Stack Control (EL0) */ > + GCSPR_EL0, /* Guarded Control Stack Pointer (EL0) */ > + > /* 32bit specific registers. */ > DACR32_EL2, /* Domain Access Control Register */ > IFSR32_EL2, /* Instruction Fault Status Register */ > @@ -481,6 +485,10 @@ enum vcpu_sysreg { > VNCR(PIR_EL1), /* Permission Indirection Register 1 (EL1) */ > VNCR(PIRE0_EL1), /* Permission Indirection Register 0 (EL1) */ > > + /* Guarded Control Stack registers */ > + VNCR(GCSPR_EL1), /* Guarded Control Stack Pointer (EL1) */ > + VNCR(GCSCR_EL1), /* Guarded Control Stack Control (EL1) */ > + > VNCR(HFGRTR_EL2), > VNCR(HFGWTR_EL2), > VNCR(HFGITR_EL2), > @@ -1343,6 +1351,12 @@ static inline bool __vcpu_has_feature(const struct kvm_arch *ka, int feature) > > #define kvm_vcpu_initialized(v) vcpu_get_flag(vcpu, VCPU_INITIALIZED) > > +static inline bool has_gcs(void) > +{ > + return IS_ENABLED(CONFIG_ARM64_GCS) && > + cpus_have_final_cap(ARM64_HAS_GCS); > +} This is mostly useless, see below. > + > int kvm_trng_call(struct kvm_vcpu *vcpu); > #ifdef CONFIG_KVM > extern phys_addr_t hyp_mem_base; > diff --git a/arch/arm64/include/asm/vncr_mapping.h b/arch/arm64/include/asm/vncr_mapping.h > index df2c47c55972..5e83e6f579fd 100644 > --- a/arch/arm64/include/asm/vncr_mapping.h > +++ b/arch/arm64/include/asm/vncr_mapping.h > @@ -88,6 +88,8 @@ > #define VNCR_PMSIRR_EL1 0x840 > #define VNCR_PMSLATFR_EL1 0x848 > #define VNCR_TRFCR_EL1 0x880 > +#define VNCR_GCSPR_EL1 0x8C0 > +#define VNCR_GCSCR_EL1 0x8D0 > #define VNCR_MPAM1_EL1 0x900 > #define VNCR_MPAMHCR_EL2 0x930 > #define VNCR_MPAMVPMV_EL2 0x938 > diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > index 4be6a7fa0070..b20212d80e9b 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > @@ -16,6 +16,27 @@ > #include > #include > > +static inline struct kvm_vcpu *ctxt_to_vcpu(struct kvm_cpu_context *ctxt) > +{ > + struct kvm_vcpu *vcpu = ctxt->__hyp_running_vcpu; > + > + if (!vcpu) > + vcpu = container_of(ctxt, struct kvm_vcpu, arch.ctxt); > + > + return vcpu; > +} > + > +static inline bool ctxt_has_gcs(struct kvm_cpu_context *ctxt) > +{ > + struct kvm_vcpu *vcpu; > + > + if (!cpus_have_final_cap(ARM64_HAS_GCS)) > + return false; > + > + vcpu = ctxt_to_vcpu(ctxt); > + return kvm_has_feat(kern_hyp_va(vcpu->kvm), ID_AA64PFR1_EL1, GCS, IMP); > +} > + > static inline void __sysreg_save_common_state(struct kvm_cpu_context *ctxt) > { > ctxt_sys_reg(ctxt, MDSCR_EL1) = read_sysreg(mdscr_el1); > @@ -25,16 +46,8 @@ static inline void __sysreg_save_user_state(struct kvm_cpu_context *ctxt) > { > ctxt_sys_reg(ctxt, TPIDR_EL0) = read_sysreg(tpidr_el0); > ctxt_sys_reg(ctxt, TPIDRRO_EL0) = read_sysreg(tpidrro_el0); > -} > - > -static inline struct kvm_vcpu *ctxt_to_vcpu(struct kvm_cpu_context *ctxt) > -{ > - struct kvm_vcpu *vcpu = ctxt->__hyp_running_vcpu; > - > - if (!vcpu) > - vcpu = container_of(ctxt, struct kvm_vcpu, arch.ctxt); > - > - return vcpu; > + if (ctxt_has_gcs(ctxt)) > + ctxt_sys_reg(ctxt, GCSPR_EL0) = read_sysreg_s(SYS_GCSPR_EL0); > } > > static inline bool ctxt_has_mte(struct kvm_cpu_context *ctxt) > @@ -80,6 +93,12 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt) > ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg_par(); > ctxt_sys_reg(ctxt, TPIDR_EL1) = read_sysreg(tpidr_el1); > > + if (ctxt_has_gcs(ctxt)) { Since this is conditioned on S1PIE, it should be only be evaluated when PIE is enabled in the guest. > + ctxt_sys_reg(ctxt, GCSPR_EL1) = read_sysreg_el1(SYS_GCSPR); > + ctxt_sys_reg(ctxt, GCSCR_EL1) = read_sysreg_el1(SYS_GCSCR); > + ctxt_sys_reg(ctxt, GCSCRE0_EL1) = read_sysreg_s(SYS_GCSCRE0_EL1); Why is this part of the EL1 context? It clearly only matters to EL0 execution, so it could be switched in load/put on nVHE as well. And actually, given that the whole thing is strictly for userspace, why do we switch *anything* eagerly at all? > + } > + > if (ctxt_has_mte(ctxt)) { > ctxt_sys_reg(ctxt, TFSR_EL1) = read_sysreg_el1(SYS_TFSR); > ctxt_sys_reg(ctxt, TFSRE0_EL1) = read_sysreg_s(SYS_TFSRE0_EL1); > @@ -113,6 +132,8 @@ static inline void __sysreg_restore_user_state(struct kvm_cpu_context *ctxt) > { > write_sysreg(ctxt_sys_reg(ctxt, TPIDR_EL0), tpidr_el0); > write_sysreg(ctxt_sys_reg(ctxt, TPIDRRO_EL0), tpidrro_el0); > + if (ctxt_has_gcs(ctxt)) > + write_sysreg_s(ctxt_sys_reg(ctxt, GCSPR_EL0), SYS_GCSPR_EL0); > } > > static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt) > @@ -156,6 +177,13 @@ static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt) > write_sysreg(ctxt_sys_reg(ctxt, PAR_EL1), par_el1); > write_sysreg(ctxt_sys_reg(ctxt, TPIDR_EL1), tpidr_el1); > > + if (ctxt_has_gcs(ctxt)) { > + write_sysreg_el1(ctxt_sys_reg(ctxt, GCSPR_EL1), SYS_GCSPR); > + write_sysreg_el1(ctxt_sys_reg(ctxt, GCSCR_EL1), SYS_GCSCR); > + write_sysreg_s(ctxt_sys_reg(ctxt, GCSCRE0_EL1), > + SYS_GCSCRE0_EL1); > + } > + > if (ctxt_has_mte(ctxt)) { > write_sysreg_el1(ctxt_sys_reg(ctxt, TFSR_EL1), SYS_TFSR); > write_sysreg_s(ctxt_sys_reg(ctxt, TFSRE0_EL1), SYS_TFSRE0_EL1); > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 22b45a15d068..cf068dcfbd49 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -2015,6 +2015,23 @@ static unsigned int mte_visibility(const struct kvm_vcpu *vcpu, > .visibility = mte_visibility, \ > } > > +static unsigned int gcs_visibility(const struct kvm_vcpu *vcpu, > + const struct sys_reg_desc *rd) > +{ > + if (has_gcs()) > + return 0; No. we've been here before. > + > + return REG_HIDDEN; > +} > + > +#define GCS_REG(name) { \ > + SYS_DESC(SYS_##name), \ > + .access = undef_access, \ > + .reset = reset_unknown, \ > + .reg = name, \ > + .visibility = gcs_visibility, \ > +} > + > static unsigned int el2_visibility(const struct kvm_vcpu *vcpu, > const struct sys_reg_desc *rd) > { > @@ -2306,7 +2323,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { > ID_AA64PFR0_EL1_GIC | > ID_AA64PFR0_EL1_AdvSIMD | > ID_AA64PFR0_EL1_FP), }, > - ID_SANITISED(ID_AA64PFR1_EL1), > + ID_WRITABLE(ID_AA64PFR1_EL1, ~(ID_AA64PFR1_EL1_RES0 | > + ID_AA64PFR1_EL1_BT)), I don't know what you're trying to do here, but that's not right. If you want to make this register writable, here's the shopping list: https://lore.kernel.org/all/87ikxsi0v9.wl-maz@kernel.org/ > ID_UNALLOCATED(4,2), > ID_UNALLOCATED(4,3), > ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0), > @@ -2390,6 +2408,10 @@ static const struct sys_reg_desc sys_reg_descs[] = { > PTRAUTH_KEY(APDB), > PTRAUTH_KEY(APGA), > > + GCS_REG(GCSCR_EL1), > + GCS_REG(GCSPR_EL1), > + GCS_REG(GCSCRE0_EL1), > + > { SYS_DESC(SYS_SPSR_EL1), access_spsr}, > { SYS_DESC(SYS_ELR_EL1), access_elr}, > > @@ -2476,6 +2498,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { > { SYS_DESC(SYS_SMIDR_EL1), undef_access }, > { SYS_DESC(SYS_CSSELR_EL1), access_csselr, reset_unknown, CSSELR_EL1 }, > { SYS_DESC(SYS_CTR_EL0), access_ctr }, > + GCS_REG(GCSPR_EL0), > { SYS_DESC(SYS_SVCR), undef_access }, > > { PMU_SYS_REG(PMCR_EL0), .access = access_pmcr, .reset = reset_pmcr, I don't see the vcpu's hcrx_el2 being updated to enable GCS. How does it work then? I also don't see the FGU updates when GCS is disabled, nor the corresponding FGT bits being marked as RES0. M. -- Without deviation from the norm, progress is not possible.