Messages in this thread | | | Subject | Re: [RFC PATCH 1/2] arm64: kvm: Save/restore MTE registers | From | Steven Price <> | Date | Thu, 18 Jun 2020 11:43:56 +0100 |
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On 17/06/2020 15:05, Catalin Marinas wrote: > 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.
Ah, thanks for pointing that out - I'd got myself confused with the whole VHE _EL12 registers. I'd managed to miss that TFSR is banked.
> 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).
I hadn't noticed that there was a different set for the non-VHE case which was missing ITFSB - I'll update that.
Thanks,
Steve
>> /* >> * 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. >
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