linux-kernel - [PATCH v9 19/22] RISC-V: KVM: Remove per-CPU vsip

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Date:   Wed, 16 Oct 2019 16:12:03 +0000
From:   Anup Patel <Anup.Patel@....com>
To:     Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim K <rkrcmar@...hat.com>
CC:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexander Graf <graf@...zon.com>,
        Atish Patra <Atish.Patra@....com>,
        Alistair Francis <Alistair.Francis@....com>,
        Damien Le Moal <Damien.LeMoal@....com>,
        Christoph Hellwig <hch@...radead.org>,
        Anup Patel <anup@...infault.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Anup Patel <Anup.Patel@....com>
Subject: [PATCH v9 19/22] RISC-V: KVM: Remove per-CPU vsip_shadow variable

Currently, we track last value wrote to VSIP CSR using per-CPU
vsip_shadow variable but this easily goes out-of-sync because
Guest can update VSIP.SSIP bit directly.

To simplify things, we remove per-CPU vsip_shadow variable and
unconditionally write vcpu->arch.guest_csr.vsip to VSIP CSR in
run-loop.

Signed-off-by: Anup Patel <anup.patel@....com>
---
 arch/riscv/include/asm/kvm_host.h |  3 ---
 arch/riscv/kvm/main.c             |  6 ------
 arch/riscv/kvm/vcpu.c             | 24 +-----------------------
 3 files changed, 1 insertion(+), 32 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index ec1ca4bc98f2..cd86acaed055 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -202,9 +202,6 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
-int kvm_riscv_setup_vsip(void);
-void kvm_riscv_cleanup_vsip(void);
-
 #define KVM_ARCH_WANT_MMU_NOTIFIER
 int kvm_unmap_hva_range(struct kvm *kvm,
 			unsigned long start, unsigned long end);
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 55df85184241..002301a27d29 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -61,17 +61,11 @@ void kvm_arch_hardware_disable(void)
 
 int kvm_arch_init(void *opaque)
 {
-	int ret;
-
 	if (!riscv_isa_extension_available(NULL, h)) {
 		kvm_info("hypervisor extension not available\n");
 		return -ENODEV;
 	}
 
-	ret = kvm_riscv_setup_vsip();
-	if (ret)
-		return ret;
-
 	kvm_riscv_stage2_vmid_detect();
 
 	kvm_info("hypervisor extension available\n");
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index fd77cd39dd8c..f1a218d3a8cf 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -111,8 +111,6 @@ static void kvm_riscv_vcpu_host_fp_restore(struct kvm_cpu_context *cntx) {}
 				 riscv_isa_extension_mask(s) | \
 				 riscv_isa_extension_mask(u))
 
-static unsigned long __percpu *vsip_shadow;
-
 static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
@@ -765,7 +763,6 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
-	unsigned long *vsip = raw_cpu_ptr(vsip_shadow);
 
 	csr_write(CSR_VSSTATUS, csr->vsstatus);
 	csr_write(CSR_VSIE, csr->vsie);
@@ -775,7 +772,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	csr_write(CSR_VSCAUSE, csr->vscause);
 	csr_write(CSR_VSTVAL, csr->vstval);
 	csr_write(CSR_VSIP, csr->vsip);
-	*vsip = csr->vsip;
 	csr_write(CSR_VSATP, csr->vsatp);
 
 	kvm_riscv_stage2_update_hgatp(vcpu);
@@ -843,26 +839,8 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
 static void kvm_riscv_update_vsip(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
-	unsigned long *vsip = raw_cpu_ptr(vsip_shadow);
-
-	if (*vsip != csr->vsip) {
-		csr_write(CSR_VSIP, csr->vsip);
-		*vsip = csr->vsip;
-	}
-}
-
-int kvm_riscv_setup_vsip(void)
-{
-	vsip_shadow = alloc_percpu(unsigned long);
-	if (!vsip_shadow)
-		return -ENOMEM;
 
-	return 0;
-}
-
-void kvm_riscv_cleanup_vsip(void)
-{
-	free_percpu(vsip_shadow);
+	csr_write(CSR_VSIP, csr->vsip);
 }
 
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
-- 
2.17.1