On Tue, Apr 02, 2019 at 07:57:12AM +0530, Amit Daniel Kachhap wrote: > From: Mark Rutland <mark.rutl...@arm.com> > > When restoring HCR_EL2 for the host, KVM uses HCR_HOST_VHE_FLAGS, which > is a constant value. This works today, as the host HCR_EL2 value is > always the same, but this will get in the way of supporting extensions > that require HCR_EL2 bits to be set conditionally for the host. > > To allow such features to work without KVM having to explicitly handle > every possible host feature combination, this patch has KVM save/restore > for the host HCR when switching to/from a guest HCR. The saving of the > register is done once during cpu hypervisor initialization state and is > just restored after switch from guest. > > For fetching HCR_EL2 during kvm initialisation, a hyp call is made using > kvm_call_hyp and is helpful in non-VHE case. > > For the hyp TLB maintenance code, __tlb_switch_to_host_vhe() is updated > to toggle the TGE bit with a RMW sequence, as we already do in > __tlb_switch_to_guest_vhe(). > > The value of hcr_el2 is now stored in struct kvm_cpu_context as both host > and guest can now use this field in a common way. > > Signed-off-by: Mark Rutland <mark.rutl...@arm.com> > [Added cpu_init_host_ctxt, hcr_el2 field in struct kvm_cpu_context, > save hcr_el2 in hyp init stage] > Signed-off-by: Amit Daniel Kachhap <amit.kach...@arm.com> > Reviewed-by: James Morse <james.mo...@arm.com> > Cc: Marc Zyngier <marc.zyng...@arm.com> > Cc: Christoffer Dall <christoffer.d...@arm.com> > Cc: kvmarm@lists.cs.columbia.edu
[...] > diff --git a/arch/arm64/include/asm/kvm_host.h > b/arch/arm64/include/asm/kvm_host.h > index a01fe087..3b09fd0 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -209,6 +209,8 @@ struct kvm_cpu_context { > u32 copro[NR_COPRO_REGS]; > }; > > + /* HYP host/guest configuration */ > + u64 hcr_el2; Minor nit: You could delete "host/guest" from the comment here. This is implied by the fact that the member is in struct kvm_cpu_context in the first place. > struct kvm_vcpu *__hyp_running_vcpu; > }; [...] > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index 3563fe6..f5cefa1 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c [...] > @@ -159,9 +159,10 @@ static void deactivate_traps_vhe(void) > } > NOKPROBE_SYMBOL(deactivate_traps_vhe); > > -static void __hyp_text __deactivate_traps_nvhe(void) > +static void __hyp_text __deactivate_traps_nvhe(struct kvm_cpu_context > *host_ctxt) Where __hyp_text functions accept pointer arguments, they are usually hyp pointers already... (see below) > { > u64 mdcr_el2 = read_sysreg(mdcr_el2); > + struct kvm_cpu_context *hyp_host_ctxt = kern_hyp_va(host_ctxt); > > __deactivate_traps_common(); > > @@ -169,25 +170,28 @@ static void __hyp_text __deactivate_traps_nvhe(void) > mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT; > > write_sysreg(mdcr_el2, mdcr_el2); > - write_sysreg(HCR_HOST_NVHE_FLAGS, hcr_el2); > + write_sysreg(hyp_host_ctxt->hcr_el2, hcr_el2); > write_sysreg(CPTR_EL2_DEFAULT, cptr_el2); > } > > static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu) > { > + struct kvm_cpu_context *host_ctxt; > + > + host_ctxt = vcpu->arch.host_cpu_context; host_ctxt is not otherwise used here, so can we convert it up-front so that the argument to __deactivate_traps_nvhe() and deactivate_traps_vhe() is a hyp pointer already? So: struct kvm_cpu_context *hyp_host_ctxt; hyp_host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); > /* > * If we pended a virtual abort, preserve it until it gets > * cleared. See D1.14.3 (Virtual Interrupts) for details, but > * the crucial bit is "On taking a vSError interrupt, > * HCR_EL2.VSE is cleared to 0." > */ > - if (vcpu->arch.hcr_el2 & HCR_VSE) > - vcpu->arch.hcr_el2 = read_sysreg(hcr_el2); > + if (vcpu->arch.ctxt.hcr_el2 & HCR_VSE) > + vcpu->arch.ctxt.hcr_el2 = read_sysreg(hcr_el2); > > if (has_vhe()) > - deactivate_traps_vhe(); > + deactivate_traps_vhe(host_ctxt); > else > - __deactivate_traps_nvhe(); > + __deactivate_traps_nvhe(host_ctxt); Then just pass hyp_host_ctxt to both of these, and drop the kern_hyp_va() conversion from __deactivate_traps_nvhe(). This may be a bit less confusing. Alternatively, just pass in the vcpu pointer (since this pattern is already well established all over the place). Another option could be to pull the hcr_el2 write out of the backends entirely and put it in this common code instead. This doesn't look straightforward though (or at least, I don't remember enough about how all these traps handling functions fit together...) [...] Cheers ---Dave _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm