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From: Anup Patel <apatel@ventanamicro.com>
To: Atish Patra <atish.patra@linux.dev>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Andrew Jones <ajones@ventanamicro.com>,
	Anup Patel <anup@brainfault.org>,
	kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	Anup Patel <apatel@ventanamicro.com>
Subject: [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set_pte() when PTE is unchanged
Date: Thu,  5 Jun 2025 11:44:52 +0530	[thread overview]
Message-ID: <20250605061458.196003-8-apatel@ventanamicro.com> (raw)
In-Reply-To: <20250605061458.196003-1-apatel@ventanamicro.com>

The gstage_set_pte() should flush remote TLB only when a leaf PTE
changes so that unnecessary remote TLB flushes can be avoided.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 arch/riscv/kvm/mmu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 1087ea74567b..d4eb1999b794 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -167,9 +167,11 @@ static int gstage_set_pte(struct kvm *kvm, u32 level,
 		ptep = &next_ptep[gstage_pte_index(addr, current_level)];
 	}
 
-	set_pte(ptep, *new_pte);
-	if (gstage_pte_leaf(ptep))
-		gstage_remote_tlb_flush(kvm, current_level, addr);
+	if (pte_val(*ptep) != pte_val(*new_pte)) {
+		set_pte(ptep, *new_pte);
+		if (gstage_pte_leaf(ptep))
+			gstage_remote_tlb_flush(kvm, current_level, addr);
+	}
 
 	return 0;
 }
-- 
2.43.0


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WARNING: multiple messages have this Message-ID (diff)
From: Anup Patel <apatel@ventanamicro.com>
To: Atish Patra <atish.patra@linux.dev>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Andrew Jones <ajones@ventanamicro.com>,
	Anup Patel <anup@brainfault.org>,
	kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	Anup Patel <apatel@ventanamicro.com>
Subject: [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set_pte() when PTE is unchanged
Date: Thu,  5 Jun 2025 11:44:52 +0530	[thread overview]
Message-ID: <20250605061458.196003-8-apatel@ventanamicro.com> (raw)
In-Reply-To: <20250605061458.196003-1-apatel@ventanamicro.com>

The gstage_set_pte() should flush remote TLB only when a leaf PTE
changes so that unnecessary remote TLB flushes can be avoided.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 arch/riscv/kvm/mmu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 1087ea74567b..d4eb1999b794 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -167,9 +167,11 @@ static int gstage_set_pte(struct kvm *kvm, u32 level,
 		ptep = &next_ptep[gstage_pte_index(addr, current_level)];
 	}
 
-	set_pte(ptep, *new_pte);
-	if (gstage_pte_leaf(ptep))
-		gstage_remote_tlb_flush(kvm, current_level, addr);
+	if (pte_val(*ptep) != pte_val(*new_pte)) {
+		set_pte(ptep, *new_pte);
+		if (gstage_pte_leaf(ptep))
+			gstage_remote_tlb_flush(kvm, current_level, addr);
+	}
 
 	return 0;
 }
-- 
2.43.0


WARNING: multiple messages have this Message-ID (diff)
From: Anup Patel <apatel@ventanamicro.com>
To: Atish Patra <atish.patra@linux.dev>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Andrew Jones <ajones@ventanamicro.com>,
	Anup Patel <anup@brainfault.org>,
	kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	Anup Patel <apatel@ventanamicro.com>
Subject: [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set_pte() when PTE is unchanged
Date: Thu,  5 Jun 2025 11:44:52 +0530	[thread overview]
Message-ID: <20250605061458.196003-8-apatel@ventanamicro.com> (raw)
In-Reply-To: <20250605061458.196003-1-apatel@ventanamicro.com>

The gstage_set_pte() should flush remote TLB only when a leaf PTE
changes so that unnecessary remote TLB flushes can be avoided.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 arch/riscv/kvm/mmu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 1087ea74567b..d4eb1999b794 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -167,9 +167,11 @@ static int gstage_set_pte(struct kvm *kvm, u32 level,
 		ptep = &next_ptep[gstage_pte_index(addr, current_level)];
 	}
 
-	set_pte(ptep, *new_pte);
-	if (gstage_pte_leaf(ptep))
-		gstage_remote_tlb_flush(kvm, current_level, addr);
+	if (pte_val(*ptep) != pte_val(*new_pte)) {
+		set_pte(ptep, *new_pte);
+		if (gstage_pte_leaf(ptep))
+			gstage_remote_tlb_flush(kvm, current_level, addr);
+	}
 
 	return 0;
 }
-- 
2.43.0


_______________________________________________
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  parent reply	other threads:[~2025-06-05  6:15 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-05  6:14 [PATCH 00/13] MMU related improvements for KVM RISC-V Anup Patel
2025-06-05  6:14 ` Anup Patel
2025-06-05  6:14 ` Anup Patel
2025-06-05  6:14 ` [PATCH 01/13] RISC-V: KVM: Fix the size parameter check in SBI SFENCE calls Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-06  0:00   ` Atish Patra
2025-06-06  0:00     ` Atish Patra
2025-06-06  0:00     ` Atish Patra
2025-06-09  4:43   ` Anup Patel
2025-06-09  4:43     ` Anup Patel
2025-06-09  4:43     ` Anup Patel
2025-06-05  6:14 ` [PATCH 02/13] RISC-V: KVM: Don't treat SBI HFENCE calls as NOPs Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-06  0:11   ` Atish Patra
2025-06-06  0:11     ` Atish Patra
2025-06-06  0:11     ` Atish Patra
2025-06-09  4:43   ` Anup Patel
2025-06-09  4:43     ` Anup Patel
2025-06-09  4:43     ` Anup Patel
2025-06-05  6:14 ` [PATCH 03/13] RISC-V: KVM: Check kvm_riscv_vcpu_alloc_vector_context() return value Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-06  0:16   ` Atish Patra
2025-06-06  0:16     ` Atish Patra
2025-06-06  0:16     ` Atish Patra
2025-06-09  5:01     ` Anup Patel
2025-06-09  5:01       ` Anup Patel
2025-06-09  5:01       ` Anup Patel
2025-06-05  6:14 ` [PATCH 04/13] RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init() Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-06  0:52   ` Atish Patra
2025-06-06  0:52     ` Atish Patra
2025-06-06  0:52     ` Atish Patra
2025-06-06  4:14   ` Nutty Liu
2025-06-06  4:14     ` Nutty Liu
2025-06-06  4:14     ` Nutty Liu
2025-06-05  6:14 ` [PATCH 05/13] RISC-V: KVM: Rename and move kvm_riscv_local_tlb_sanitize() Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-06  1:21   ` Atish Patra
2025-06-06  1:21     ` Atish Patra
2025-06-06  1:21     ` Atish Patra
2025-06-06  4:25   ` Nutty Liu
2025-06-06  4:25     ` Nutty Liu
2025-06-06  4:25     ` Nutty Liu
2025-06-05  6:14 ` [PATCH 06/13] RISC-V: KVM: Replace KVM_REQ_HFENCE_GVMA_VMID_ALL with KVM_REQ_TLB_FLUSH Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-06  1:24   ` Atish Patra
2025-06-06  1:24     ` Atish Patra
2025-06-06  1:24     ` Atish Patra
2025-06-05  6:14 ` Anup Patel [this message]
2025-06-05  6:14   ` [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set_pte() when PTE is unchanged Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14 ` [PATCH 08/13] RISC-V: KVM: Implement kvm_arch_flush_remote_tlbs_range() Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14 ` [PATCH 09/13] RISC-V: KVM: Factor-out MMU related declarations into separate headers Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14 ` [PATCH 10/13] RISC-V: KVM: Introduce struct kvm_gstage_mapping Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14 ` [PATCH 11/13] RISC-V: KVM: Add vmid field to struct kvm_riscv_hfence Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14 ` [PATCH 12/13] RISC-V: KVM: Factor-out g-stage page table management Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14 ` [PATCH 13/13] RISC-V: KVM: Pass VMID as parameter to kvm_riscv_hfence_xyz() APIs Anup Patel
2025-06-05  6:14   ` Anup Patel
2025-06-05  6:14   ` Anup Patel

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