| Message ID | 20230119173559.2517103-3-dmatlack@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Add a common API for range-based TLB invalidation | expand |
Hi David, On Thu, Jan 19, 2023 at 09:35:54AM -0800, David Matlack wrote: > Use kvm_arch_flush_remote_tlbs() instead of > CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL. The two mechanisms solve the same > problem, allowing architecture-specific code to provide a non-IPI > implementation of remote TLB flushing. > > Dropping CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL allows KVM to standardize > all architectures on kvm_arch_flush_remote_tlbs() instead of maintaining > two mechanisms. > > Opt to standardize on kvm_arch_flush_remote_tlbs() since it avoids > duplicating the generic TLB stats across architectures that implement > their own remote TLB flush. > > This adds an extra function call to the ARM64 kvm_flush_remote_tlbs() > path, but (I assume) that is a small cost in comparison to flushing > remote TLBs. A fair assumption indeed. The real pile up occurs on the DSB subsequent to the TLBI. > No functional change intended. > > Signed-off-by: David Matlack <dmatlack@google.com> > --- > arch/arm64/include/asm/kvm_host.h | 3 +++ > arch/arm64/kvm/Kconfig | 1 - > arch/arm64/kvm/mmu.c | 6 +++--- > virt/kvm/kvm_main.c | 2 -- > 4 files changed, 6 insertions(+), 6 deletions(-) I think you're missing the diff that actually drops the Kconfig opton from virt/kvm/Kconfig. -- Thanks, Oliver
On Tue, Jan 24, 2023 at 9:17 AM Oliver Upton <oliver.upton@linux.dev> wrote: > On Thu, Jan 19, 2023 at 09:35:54AM -0800, David Matlack wrote: > > > > arch/arm64/include/asm/kvm_host.h | 3 +++ > > arch/arm64/kvm/Kconfig | 1 - > > arch/arm64/kvm/mmu.c | 6 +++--- > > virt/kvm/kvm_main.c | 2 -- > > 4 files changed, 6 insertions(+), 6 deletions(-) > > I think you're missing the diff that actually drops the Kconfig opton > from virt/kvm/Kconfig. Indeed I am, thanks for catching that!
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 113e20fdbb56..062800f1dc54 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -998,6 +998,9 @@ int __init kvm_set_ipa_limit(void); #define __KVM_HAVE_ARCH_VM_ALLOC struct kvm *kvm_arch_alloc_vm(void); +#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS +int kvm_arch_flush_remote_tlbs(struct kvm *kvm); + static inline bool kvm_vm_is_protected(struct kvm *kvm) { return false; diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index ca6eadeb7d1a..e9ac57098a0b 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -25,7 +25,6 @@ menuconfig KVM select MMU_NOTIFIER select PREEMPT_NOTIFIERS select HAVE_KVM_CPU_RELAX_INTERCEPT - select HAVE_KVM_ARCH_TLB_FLUSH_ALL select KVM_MMIO select KVM_GENERIC_DIRTYLOG_READ_PROTECT select KVM_XFER_TO_GUEST_WORK diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 01352f5838a0..8840f65e0e40 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -80,15 +80,15 @@ static bool memslot_is_logging(struct kvm_memory_slot *memslot) } /** - * kvm_flush_remote_tlbs() - flush all VM TLB entries for v7/8 + * kvm_arch_flush_remote_tlbs() - flush all VM TLB entries for v7/8 * @kvm: pointer to kvm structure. * * Interface to HYP function to flush all VM TLB entries */ -void kvm_flush_remote_tlbs(struct kvm *kvm) +int kvm_arch_flush_remote_tlbs(struct kvm *kvm) { - ++kvm->stat.generic.remote_tlb_flush_requests; kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu); + return 0; } static bool kvm_is_device_pfn(unsigned long pfn) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 277507463678..fefd3e3c8fe1 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -347,7 +347,6 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req) } EXPORT_SYMBOL_GPL(kvm_make_all_cpus_request); -#ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL void kvm_flush_remote_tlbs(struct kvm *kvm) { ++kvm->stat.generic.remote_tlb_flush_requests; @@ -368,7 +367,6 @@ void kvm_flush_remote_tlbs(struct kvm *kvm) ++kvm->stat.generic.remote_tlb_flush; } EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs); -#endif static void kvm_flush_shadow_all(struct kvm *kvm) {
Use kvm_arch_flush_remote_tlbs() instead of CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL. The two mechanisms solve the same problem, allowing architecture-specific code to provide a non-IPI implementation of remote TLB flushing. Dropping CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL allows KVM to standardize all architectures on kvm_arch_flush_remote_tlbs() instead of maintaining two mechanisms. Opt to standardize on kvm_arch_flush_remote_tlbs() since it avoids duplicating the generic TLB stats across architectures that implement their own remote TLB flush. This adds an extra function call to the ARM64 kvm_flush_remote_tlbs() path, but (I assume) that is a small cost in comparison to flushing remote TLBs. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> --- arch/arm64/include/asm/kvm_host.h | 3 +++ arch/arm64/kvm/Kconfig | 1 - arch/arm64/kvm/mmu.c | 6 +++--- virt/kvm/kvm_main.c | 2 -- 4 files changed, 6 insertions(+), 6 deletions(-)