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Fri, 12 Sep 2025 22:01:47 +0800 From: fangyu.yu@linux.alibaba.com To: fangyu.yu@linux.alibaba.com Cc: alex@ghiti.fr, anup@brainfault.org, aou@eecs.berkeley.edu, atish.patra@linux.dev, graf@amazon.com, guoren@kernel.org, jiangyifei@huawei.com, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, palmer@dabbelt.com, paul.walmsley@sifive.com, pbonzini@redhat.com Subject: [PATCH] RISC-V: KVM: Fix guest page fault within HLV* instructions Date: Fri, 12 Sep 2025 22:01:42 +0800 Message-Id: <20250912140142.25147-1-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20250912134332.22053-1-fangyu.yu@linux.alibaba.com> References: <20250912134332.22053-1-fangyu.yu@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit >From: Fangyu Yu > >When executing HLV* instructions at the HS mode, a guest page fault >may occur when a g-stage page table migration between triggering the >virtual instruction exception and executing the HLV* instruction. > >This may be a corner case, and one simpler way to handle this is to >re-execute the instruction where the virtual instruction exception >occurred, and the guest page fault will be automatically handled. > >Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU") >Signed-off-by: Fangyu Yu >--- > arch/riscv/kvm/vcpu_insn.c | 21 ++++++++++++++++++--- > 1 file changed, 18 insertions(+), 3 deletions(-) > >diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c >index 97dec18e6989..a8b93aa4d8ec 100644 >--- a/arch/riscv/kvm/vcpu_insn.c >+++ b/arch/riscv/kvm/vcpu_insn.c >@@ -448,7 +448,12 @@ int kvm_riscv_vcpu_virtual_insn(struct kvm_vcpu *vcpu, struct kvm_run *run, > insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, > ct->sepc, > &utrap); >- if (utrap.scause) { >+ switch (utrap.scause) { >+ case 0: >+ break; >+ case EXC_LOAD_GUEST_PAGE_FAULT: >+ return KVM_INSN_CONTINUE_SAME_SEPC; >+ default: > utrap.sepc = ct->sepc; > kvm_riscv_vcpu_trap_redirect(vcpu, &utrap); > return 1; >@@ -503,7 +508,12 @@ int kvm_riscv_vcpu_mmio_load(struct kvm_vcpu *vcpu, struct kvm_run *run, > */ > insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc, > &utrap); >- if (utrap.scause) { >+ switch (utrap.scause) { >+ case 0: >+ break; >+ case EXC_LOAD_GUEST_PAGE_FAULT: >+ return KVM_INSN_CONTINUE_SAME_SEPC; >+ default: > /* Redirect trap if we failed to read instruction */ > utrap.sepc = ct->sepc; > kvm_riscv_vcpu_trap_redirect(vcpu, &utrap); >@@ -629,7 +639,12 @@ int kvm_riscv_vcpu_mmio_store(struct kvm_vcpu *vcpu, struct kvm_run *run, > */ > insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc, > &utrap); >- if (utrap.scause) { >+ switch (utrap.scause) { >+ case 0: >+ break; >+ case EXC_LOAD_GUEST_PAGE_FAULT: Here should be EXC_STORE_GUEST_PAGE_FAULT, I will fix it next version. >+ return KVM_INSN_CONTINUE_SAME_SEPC; >+ default: > /* Redirect trap if we failed to read instruction */ > utrap.sepc = ct->sepc; > kvm_riscv_vcpu_trap_redirect(vcpu, &utrap); >-- >2.49.0