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Tue, 17 Nov 2020 19:20:34 +0000 MIME-Version: 1.0 Date: Tue, 17 Nov 2020 19:20:34 +0000 From: Marc Zyngier To: Steven Price Subject: Re: [PATCH v4 1/2] arm64: kvm: Save/restore MTE registers In-Reply-To: <20201026155727.36685-2-steven.price@arm.com> References: <20201026155727.36685-1-steven.price@arm.com> <20201026155727.36685-2-steven.price@arm.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: steven.price@arm.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave.Martin@arm.com, mark.rutland@arm.com, tglx@linutronix.de, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, richard.henderson@linaro.org, peter.maydell@linaro.org, Haibo.Xu@arm.com, drjones@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201117_142038_421962_1B85C4A9 X-CRM114-Status: GOOD ( 26.30 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Maydell , "Dr. David Alan Gilbert" , Andrew Jones , Haibo Xu , Suzuki K Poulose , qemu-devel@nongnu.org, Catalin Marinas , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Dave Martin , James Morse , linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Steven, These patches unfortunately don't apply to -rc4 anymore, as we repainted quite a bit while working on fixes. I'd be grateful if you could rebase them. A few other things though: On 2020-10-26 15:57, Steven Price wrote: > Define the new system registers that MTE introduces and context switch > them. The MTE feature is still hidden from the ID register as it isn't > supported in a VM yet. > > Signed-off-by: Steven Price > Reviewed-by: Andrew Jones > --- > arch/arm64/include/asm/kvm_host.h | 4 ++++ > arch/arm64/include/asm/sysreg.h | 3 ++- > arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 14 ++++++++++++++ > arch/arm64/kvm/sys_regs.c | 14 ++++++++++---- > 4 files changed, 30 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h > b/arch/arm64/include/asm/kvm_host.h > index 0aecbab6a7fb..95ab7345dcc8 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -134,6 +134,8 @@ enum vcpu_sysreg { > SCTLR_EL1, /* System Control Register */ > ACTLR_EL1, /* Auxiliary Control Register */ > CPACR_EL1, /* Coprocessor Access Control */ > + RGSR_EL1, /* Random Allocation Tag Seed Register */ > + GCR_EL1, /* Tag Control Register */ > ZCR_EL1, /* SVE Control */ > TTBR0_EL1, /* Translation Table Base Register 0 */ > TTBR1_EL1, /* Translation Table Base Register 1 */ > @@ -150,6 +152,8 @@ enum vcpu_sysreg { > TPIDR_EL1, /* Thread ID, Privileged */ > AMAIR_EL1, /* Aux Memory Attribute Indirection Register */ > CNTKCTL_EL1, /* Timer Control Register (EL1) */ > + TFSRE0_EL1, /* Tag Fault Status Register (EL0) */ > + TFSR_EL1, /* Tag Fault Stauts Register (EL1) */ > PAR_EL1, /* Physical Address Register */ > MDSCR_EL1, /* Monitor Debug System Control Register */ > MDCCINT_EL1, /* Monitor Debug Comms Channel Interrupt Enable Reg */ > diff --git a/arch/arm64/include/asm/sysreg.h > b/arch/arm64/include/asm/sysreg.h > index d52c1b3ce589..7727df0bc09d 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -565,7 +565,8 @@ > #define SCTLR_ELx_M (BIT(0)) > > #define SCTLR_ELx_FLAGS (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | \ > - SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_IESB) > + SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_IESB | \ > + SCTLR_ELx_ITFSB) > > /* SCTLR_EL2 specific flags. */ > #define SCTLR_EL2_RES1 ((BIT(4)) | (BIT(5)) | (BIT(11)) | (BIT(16)) > | \ > diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > index 7a986030145f..a124ffa49ba3 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h > @@ -18,6 +18,11 @@ > static inline void __sysreg_save_common_state(struct kvm_cpu_context > *ctxt) > { > ctxt_sys_reg(ctxt, MDSCR_EL1) = read_sysreg(mdscr_el1); > + if (system_supports_mte()) { > + ctxt_sys_reg(ctxt, RGSR_EL1) = read_sysreg_s(SYS_RGSR_EL1); > + ctxt_sys_reg(ctxt, GCR_EL1) = read_sysreg_s(SYS_GCR_EL1); > + ctxt_sys_reg(ctxt, TFSRE0_EL1) = read_sysreg_s(SYS_TFSRE0_EL1); As far as I can tell, HCR_EL2.ATA is still clear when running a guest. So why, do we save/restore this state yet? Also, I wonder whether we should keep these in the C code. If one day we enable MTE in the kernel, we will have to move them to the assembly part, much like we do for PAuth. And I fear that "one day" is pretty soon: https://lore.kernel.org/linux-arm-kernel/cover.1605046192.git.andreyknvl@google.com/ > + } > } > > static inline void __sysreg_save_user_state(struct kvm_cpu_context > *ctxt) > @@ -45,6 +50,8 @@ static inline void __sysreg_save_el1_state(struct > kvm_cpu_context *ctxt) > ctxt_sys_reg(ctxt, CNTKCTL_EL1) = read_sysreg_el1(SYS_CNTKCTL); > ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg(par_el1); > ctxt_sys_reg(ctxt, TPIDR_EL1) = read_sysreg(tpidr_el1); > + if (system_supports_mte()) > + ctxt_sys_reg(ctxt, TFSR_EL1) = read_sysreg_el1(SYS_TFSR); > > ctxt_sys_reg(ctxt, SP_EL1) = read_sysreg(sp_el1); > ctxt_sys_reg(ctxt, ELR_EL1) = read_sysreg_el1(SYS_ELR); > @@ -63,6 +70,11 @@ static inline void > __sysreg_save_el2_return_state(struct kvm_cpu_context *ctxt) > static inline void __sysreg_restore_common_state(struct > kvm_cpu_context *ctxt) > { > write_sysreg(ctxt_sys_reg(ctxt, MDSCR_EL1), mdscr_el1); > + if (system_supports_mte()) { > + write_sysreg_s(ctxt_sys_reg(ctxt, RGSR_EL1), SYS_RGSR_EL1); > + write_sysreg_s(ctxt_sys_reg(ctxt, GCR_EL1), SYS_GCR_EL1); > + write_sysreg_s(ctxt_sys_reg(ctxt, TFSRE0_EL1), SYS_TFSRE0_EL1); > + } > } > > static inline void __sysreg_restore_user_state(struct kvm_cpu_context > *ctxt) > @@ -106,6 +118,8 @@ static inline void > __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt) > write_sysreg_el1(ctxt_sys_reg(ctxt, CNTKCTL_EL1), SYS_CNTKCTL); > write_sysreg(ctxt_sys_reg(ctxt, PAR_EL1), par_el1); > write_sysreg(ctxt_sys_reg(ctxt, TPIDR_EL1), tpidr_el1); > + if (system_supports_mte()) > + write_sysreg_el1(ctxt_sys_reg(ctxt, TFSR_EL1), SYS_TFSR); > > if (!has_vhe() && > cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT) && > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index d9117bc56237..430e36e1a13d 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1391,6 +1391,12 @@ static bool access_mte_regs(struct kvm_vcpu > *vcpu, struct sys_reg_params *p, > return false; > } > > +static unsigned int mte_visibility(const struct kvm_vcpu *vcpu, > + const struct sys_reg_desc *rd) > +{ > + return REG_HIDDEN_USER | REG_HIDDEN_GUEST; The handling of visibility has changed somehow since 01fe5ace92dd. > +} > + > /* sys_reg_desc initialiser for known cpufeature ID registers */ > #define ID_SANITISED(name) { \ > SYS_DESC(SYS_##name), \ > @@ -1557,8 +1563,8 @@ static const struct sys_reg_desc sys_reg_descs[] > = { > { SYS_DESC(SYS_ACTLR_EL1), access_actlr, reset_actlr, ACTLR_EL1 }, > { SYS_DESC(SYS_CPACR_EL1), NULL, reset_val, CPACR_EL1, 0 }, > > - { SYS_DESC(SYS_RGSR_EL1), access_mte_regs }, > - { SYS_DESC(SYS_GCR_EL1), access_mte_regs }, > + { SYS_DESC(SYS_RGSR_EL1), access_mte_regs, reset_unknown, RGSR_EL1, > .visibility = mte_visibility }, > + { SYS_DESC(SYS_GCR_EL1), access_mte_regs, reset_unknown, GCR_EL1, > .visibility = mte_visibility }, > > { SYS_DESC(SYS_ZCR_EL1), NULL, reset_val, ZCR_EL1, 0, .visibility = > sve_visibility }, > { SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 }, > @@ -1584,8 +1590,8 @@ static const struct sys_reg_desc sys_reg_descs[] > = { > { SYS_DESC(SYS_ERXMISC0_EL1), trap_raz_wi }, > { SYS_DESC(SYS_ERXMISC1_EL1), trap_raz_wi }, > > - { SYS_DESC(SYS_TFSR_EL1), access_mte_regs }, > - { SYS_DESC(SYS_TFSRE0_EL1), access_mte_regs }, > + { SYS_DESC(SYS_TFSR_EL1), access_mte_regs, reset_unknown, TFSR_EL1, > .visibility = mte_visibility }, > + { SYS_DESC(SYS_TFSRE0_EL1), access_mte_regs, reset_unknown, > TFSRE0_EL1, .visibility = mte_visibility }, > > { SYS_DESC(SYS_FAR_EL1), access_vm_reg, reset_unknown, FAR_EL1 }, > { SYS_DESC(SYS_PAR_EL1), NULL, reset_unknown, PAR_EL1 }, Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel