linux-kernel - [PATCH v6 02/11] KVM: arm64: Use kvm_arch_flush_remote

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Date:   Sat, 15 Jul 2023 00:53:56 +0000
From:   Raghavendra Rao Ananta <rananta@...gle.com>
To:     Oliver Upton <oliver.upton@...ux.dev>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        Jing Zhang <jingzhangos@...gle.com>,
        Colton Lewis <coltonlewis@...gle.com>,
        Raghavendra Rao Anata <rananta@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-mips@...r.kernel.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Zenghui Yu <zenghui.yu@...ux.dev>,
        Gavin Shan <gshan@...hat.com>
Subject: [PATCH v6 02/11] KVM: arm64: Use kvm_arch_flush_remote_tlbs()

From: David Matlack <dmatlack@...gle.com>

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 that is a small cost in comparison to flushing remote TLBs.

In addition, instead of just incrementing remote_tlb_flush_requests
stat, the generic interface would also increment the
remote_tlb_flush stat.

Signed-off-by: David Matlack <dmatlack@...gle.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
Reviewed-by: Zenghui Yu <zenghui.yu@...ux.dev>
Acked-by: Oliver Upton <oliver.upton@...ux.dev>
Reviewed-by: Gavin Shan <gshan@...hat.com>
---
 arch/arm64/include/asm/kvm_host.h | 3 +++
 arch/arm64/kvm/Kconfig            | 1 -
 arch/arm64/kvm/mmu.c              | 6 +++---
 virt/kvm/Kconfig                  | 3 ---
 virt/kvm/kvm_main.c               | 2 --
 5 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 8b6096753740..7281222f24ef 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1111,6 +1111,9 @@ 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 f531da6b362e..6b730fcfee37 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 6db9ef288ec3..0ac721fa27f1 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -161,15 +161,15 @@ 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/Kconfig b/virt/kvm/Kconfig
index b74916de5183..484d0873061c 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -62,9 +62,6 @@ config HAVE_KVM_CPU_RELAX_INTERCEPT
 config KVM_VFIO
        bool
 
-config HAVE_KVM_ARCH_TLB_FLUSH_ALL
-       bool
-
 config HAVE_KVM_INVALID_WAKEUPS
        bool
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 70e5479797ac..d6b050786155 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -345,7 +345,6 @@ 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;
@@ -366,7 +365,6 @@ 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)
 {
-- 
2.41.0.455.g037347b96a-goog