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Date: Wed, 17 Jun 2020 15:05:47 +0100 From: Catalin Marinas <catalin.marinas@....com> To: Steven Price <steven.price@....com> Cc: Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>, James Morse <james.morse@....com>, Julien Thierry <julien.thierry.kdev@...il.com>, Suzuki K Poulose <suzuki.poulose@....com>, kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Dave Martin <Dave.Martin@....com>, Mark Rutland <mark.rutland@....com>, Thomas Gleixner <tglx@...utronix.de> Subject: Re: [RFC PATCH 1/2] arm64: kvm: Save/restore MTE registers On Wed, Jun 17, 2020 at 01:38:43PM +0100, Steven Price wrote: > diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c > index 75b1925763f1..6ecee1528566 100644 > --- a/arch/arm64/kvm/hyp/sysreg-sr.c > +++ b/arch/arm64/kvm/hyp/sysreg-sr.c > @@ -26,6 +26,12 @@ > static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt) > { > ctxt->sys_regs[MDSCR_EL1] = read_sysreg(mdscr_el1); > + if (system_supports_mte()) { > + ctxt->sys_regs[RGSR_EL1] = read_sysreg_s(SYS_RGSR_EL1); > + ctxt->sys_regs[GCR_EL1] = read_sysreg_s(SYS_GCR_EL1); > + ctxt->sys_regs[TFSRE0_EL1] = read_sysreg_s(SYS_TFSRE0_EL1); > + ctxt->sys_regs[TFSR_EL1] = read_sysreg_s(SYS_TFSR_EL1); > + } TFSR_EL1 is not a common register as we have the TFSR_EL2 as well. So you'd have to access it as read_sysreg_el1(SYS_TFSR) so that, in the VHE case, it generates TFSR_EL12, otherwise you just save the host register. Also, since TFSR*_EL1 can be set asynchronously, I think we need to set the SCTLR_EL2.ITFSB bit so that the register update is synchronised on entry to EL2. With VHE we get this automatically as part of SCTLR_EL1_SET but it turns out that we have another SCTLR_ELx_FLAGS macro for the non-VHE case (why not calling this SCTLR_EL2_* I have no idea). > /* > * The host arm64 Linux uses sp_el0 to point to 'current' and it must > @@ -99,6 +105,12 @@ NOKPROBE_SYMBOL(sysreg_save_guest_state_vhe); > static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt) > { > write_sysreg(ctxt->sys_regs[MDSCR_EL1], mdscr_el1); > + if (system_supports_mte()) { > + write_sysreg_s(ctxt->sys_regs[RGSR_EL1], SYS_RGSR_EL1); > + write_sysreg_s(ctxt->sys_regs[GCR_EL1], SYS_GCR_EL1); > + write_sysreg_s(ctxt->sys_regs[TFSRE0_EL1], SYS_TFSRE0_EL1); > + write_sysreg_s(ctxt->sys_regs[TFSR_EL1], SYS_TFSR_EL1); > + } Similarly here, you override the TFSR_EL2 with VHE enabled. -- Catalin
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