Re: [PATCH v2 3/7] KVM: arm64: Implement __kvm_tlb_flush_range_vmid_ipa()

From: Oliver Upton
Date: Wed Mar 29 2023 - 20:59:30 EST


On Mon, Feb 06, 2023 at 05:23:36PM +0000, Raghavendra Rao Ananta wrote:
> Define __kvm_tlb_flush_range_vmid_ipa() (for VHE and nVHE)

bikeshed: Personally, I find that range implies it takes an address as an
argument already. Maybe just call it __kvm_tlb_flush_vmid_range()

> to flush a range of stage-2 page-tables using IPA in one go.
> If the system supports FEAT_TLBIRANGE, the following patches
> would conviniently replace global TLBI such as vmalls12e1is
> in the map, unmap, and dirty-logging paths with ripas2e1is
> instead.
>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_asm.h | 3 +++
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 12 ++++++++++++
> arch/arm64/kvm/hyp/nvhe/tlb.c | 28 ++++++++++++++++++++++++++++
> arch/arm64/kvm/hyp/vhe/tlb.c | 24 ++++++++++++++++++++++++
> 4 files changed, 67 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 995ff048e8851..80a8ea85e84f8 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -79,6 +79,7 @@ enum __kvm_host_smccc_func {
> __KVM_HOST_SMCCC_FUNC___pkvm_init_vm,
> __KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu,
> __KVM_HOST_SMCCC_FUNC___pkvm_teardown_vm,
> + __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_range_vmid_ipa,
> };
>
> #define DECLARE_KVM_VHE_SYM(sym) extern char sym[]
> @@ -243,6 +244,8 @@ extern void __kvm_flush_vm_context(void);
> extern void __kvm_flush_cpu_context(struct kvm_s2_mmu *mmu);
> extern void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu, phys_addr_t ipa,
> int level);
> +extern void __kvm_tlb_flush_range_vmid_ipa(struct kvm_s2_mmu *mmu, phys_addr_t start,
> + phys_addr_t end, int level, int tlb_level);
> extern void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu);
>
> extern void __kvm_timer_set_cntvoff(u64 cntvoff);
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> index 728e01d4536b0..5787eee4c9fe4 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> @@ -125,6 +125,17 @@ static void handle___kvm_tlb_flush_vmid_ipa(struct kvm_cpu_context *host_ctxt)
> __kvm_tlb_flush_vmid_ipa(kern_hyp_va(mmu), ipa, level);
> }
>
> +static void handle___kvm_tlb_flush_range_vmid_ipa(struct kvm_cpu_context *host_ctxt)
> +{
> + DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
> + DECLARE_REG(phys_addr_t, start, host_ctxt, 2);
> + DECLARE_REG(phys_addr_t, end, host_ctxt, 3);
> + DECLARE_REG(int, level, host_ctxt, 4);
> + DECLARE_REG(int, tlb_level, host_ctxt, 5);
> +
> + __kvm_tlb_flush_range_vmid_ipa(kern_hyp_va(mmu), start, end, level, tlb_level);
> +}
> +
> static void handle___kvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt)
> {
> DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
> @@ -315,6 +326,7 @@ static const hcall_t host_hcall[] = {
> HANDLE_FUNC(__kvm_vcpu_run),
> HANDLE_FUNC(__kvm_flush_vm_context),
> HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa),
> + HANDLE_FUNC(__kvm_tlb_flush_range_vmid_ipa),
> HANDLE_FUNC(__kvm_tlb_flush_vmid),
> HANDLE_FUNC(__kvm_flush_cpu_context),
> HANDLE_FUNC(__kvm_timer_set_cntvoff),
> diff --git a/arch/arm64/kvm/hyp/nvhe/tlb.c b/arch/arm64/kvm/hyp/nvhe/tlb.c
> index d296d617f5896..7398dd00445e7 100644
> --- a/arch/arm64/kvm/hyp/nvhe/tlb.c
> +++ b/arch/arm64/kvm/hyp/nvhe/tlb.c
> @@ -109,6 +109,34 @@ void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu,
> __tlb_switch_to_host(&cxt);
> }
>
> +void __kvm_tlb_flush_range_vmid_ipa(struct kvm_s2_mmu *mmu, phys_addr_t start,
> + phys_addr_t end, int level, int tlb_level)
> +{
> + struct tlb_inv_context cxt;
> +
> + dsb(ishst);
> +
> + /* Switch to requested VMID */
> + __tlb_switch_to_guest(mmu, &cxt);
> +
> + __kvm_tlb_flush_range(ipas2e1is, mmu, start, end, level, tlb_level);
> +
> + /*
> + * Range-based ipas2e1is flushes only Stage-2 entries, and since the
> + * VA isn't available for Stage-1 entries, flush the entire stage-1.
> + */

nit: if we are going to preserve some of the commentary over in
__kvm_tlb_flush_vmid_ipa(), I would prefer just an exact copy/paste.
But, FWIW, I think you can just elide the clarifying comments altogether
since the relationship between stage-1 and stage-2 invalidations is
already documented.

> + dsb(ish);
> + __tlbi(vmalle1is);
> + dsb(ish);
> + isb();
> +
> + /* See the comment below in __kvm_tlb_flush_vmid_ipa() */

Same comment as above.

--
Thanks,
Oliver