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Wed, 18 Jun 2025 04:36:09 -0700 (PDT) Received: from localhost.localdomain ([122.171.23.44]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-237c57c63efsm9112475ad.172.2025.06.18.04.36.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jun 2025 04:36:08 -0700 (PDT) From: Anup Patel To: Atish Patra Cc: Palmer Dabbelt , Paul Walmsley , Alexandre Ghiti , Andrew Jones , Anup Patel , kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Anup Patel , Atish Patra Subject: [PATCH v3 05/12] RISC-V: KVM: Don't flush TLB when PTE is unchanged Date: Wed, 18 Jun 2025 17:05:25 +0530 Message-ID: <20250618113532.471448-6-apatel@ventanamicro.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250618113532.471448-1-apatel@ventanamicro.com> References: <20250618113532.471448-1-apatel@ventanamicro.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250618_043610_801378_77B2E50B X-CRM114-Status: GOOD ( 11.12 ) X-BeenThere: kvm-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kvm-riscv" Errors-To: kvm-riscv-bounces+kvm-riscv=archiver.kernel.org@lists.infradead.org The gstage_set_pte() and gstage_op_pte() should flush TLB only when a leaf PTE changes so that unnecessary TLB flushes can be avoided. Reviewed-by: Atish Patra Signed-off-by: Anup Patel --- arch/riscv/kvm/mmu.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 1087ea74567b..29f1bd853a66 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; } @@ -229,7 +231,7 @@ static void gstage_op_pte(struct kvm *kvm, gpa_t addr, pte_t *ptep, u32 ptep_level, enum gstage_op op) { int i, ret; - pte_t *next_ptep; + pte_t old_pte, *next_ptep; u32 next_ptep_level; unsigned long next_page_size, page_size; @@ -258,11 +260,13 @@ static void gstage_op_pte(struct kvm *kvm, gpa_t addr, if (op == GSTAGE_OP_CLEAR) put_page(virt_to_page(next_ptep)); 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Wed, 18 Jun 2025 04:36:09 -0700 (PDT) Received: from localhost.localdomain ([122.171.23.44]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-237c57c63efsm9112475ad.172.2025.06.18.04.36.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jun 2025 04:36:08 -0700 (PDT) From: Anup Patel To: Atish Patra Cc: Palmer Dabbelt , Paul Walmsley , Alexandre Ghiti , Andrew Jones , Anup Patel , kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Anup Patel , Atish Patra Subject: [PATCH v3 05/12] RISC-V: KVM: Don't flush TLB when PTE is unchanged Date: Wed, 18 Jun 2025 17:05:25 +0530 Message-ID: <20250618113532.471448-6-apatel@ventanamicro.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250618113532.471448-1-apatel@ventanamicro.com> References: <20250618113532.471448-1-apatel@ventanamicro.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The gstage_set_pte() and gstage_op_pte() should flush TLB only when a leaf PTE changes so that unnecessary TLB flushes can be avoided. Reviewed-by: Atish Patra Signed-off-by: Anup Patel --- arch/riscv/kvm/mmu.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 1087ea74567b..29f1bd853a66 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; } @@ -229,7 +231,7 @@ static void gstage_op_pte(struct kvm *kvm, gpa_t addr, pte_t *ptep, u32 ptep_level, enum gstage_op op) { int i, ret; - pte_t *next_ptep; + pte_t old_pte, *next_ptep; u32 next_ptep_level; unsigned long next_page_size, page_size; @@ -258,11 +260,13 @@ static void gstage_op_pte(struct kvm *kvm, gpa_t addr, if (op == GSTAGE_OP_CLEAR) put_page(virt_to_page(next_ptep)); 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Wed, 18 Jun 2025 04:36:08 -0700 (PDT) From: Anup Patel To: Atish Patra Cc: Palmer Dabbelt , Paul Walmsley , Alexandre Ghiti , Andrew Jones , Anup Patel , kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Anup Patel , Atish Patra Subject: [PATCH v3 05/12] RISC-V: KVM: Don't flush TLB when PTE is unchanged Date: Wed, 18 Jun 2025 17:05:25 +0530 Message-ID: <20250618113532.471448-6-apatel@ventanamicro.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250618113532.471448-1-apatel@ventanamicro.com> References: <20250618113532.471448-1-apatel@ventanamicro.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250618_043610_804800_74EB1229 X-CRM114-Status: GOOD ( 11.12 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org The gstage_set_pte() and gstage_op_pte() should flush TLB only when a leaf PTE changes so that unnecessary TLB flushes can be avoided. Reviewed-by: Atish Patra Signed-off-by: Anup Patel --- arch/riscv/kvm/mmu.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 1087ea74567b..29f1bd853a66 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; } @@ -229,7 +231,7 @@ static void gstage_op_pte(struct kvm *kvm, gpa_t addr, pte_t *ptep, u32 ptep_level, enum gstage_op op) { int i, ret; - pte_t *next_ptep; + pte_t old_pte, *next_ptep; u32 next_ptep_level; unsigned long next_page_size, page_size; @@ -258,11 +260,13 @@ static void gstage_op_pte(struct kvm *kvm, gpa_t addr, if (op == GSTAGE_OP_CLEAR) put_page(virt_to_page(next_ptep)); } else { + old_pte = *ptep; if (op == GSTAGE_OP_CLEAR) set_pte(ptep, __pte(0)); else if (op == GSTAGE_OP_WP) set_pte(ptep, __pte(pte_val(ptep_get(ptep)) & ~_PAGE_WRITE)); - gstage_remote_tlb_flush(kvm, ptep_level, addr); + if (pte_val(*ptep) != pte_val(old_pte)) + gstage_remote_tlb_flush(kvm, ptep_level, addr); } } -- 2.43.0 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv