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From:   Anup Patel <Anup.Patel@wdc.com>
To:     Palmer Dabbelt <palmer@sifive.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Radim K <rkrcmar@redhat.com>
CC:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alexander Graf <graf@amazon.com>,
        Atish Patra <Atish.Patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Damien Le Moal <Damien.LeMoal@wdc.com>,
        Christoph Hellwig <hch@infradead.org>,
        Anup Patel <anup@brainfault.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Anup Patel <Anup.Patel@wdc.com>
Subject: [PATCH v9 19/22] RISC-V: KVM: Remove per-CPU vsip_shadow variable
Thread-Topic: [PATCH v9 19/22] RISC-V: KVM: Remove per-CPU vsip_shadow
 variable
Thread-Index: AQHVhDxyq88TV5U/o0+PXStFQacqrg==
Date:   Wed, 16 Oct 2019 16:12:03 +0000
Message-ID: <20191016160649.24622-20-anup.patel@wdc.com>
References: <20191016160649.24622-1-anup.patel@wdc.com>
In-Reply-To: <20191016160649.24622-1-anup.patel@wdc.com>
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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@wdc.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) {}
=20
-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)
=20
 int kvm_arch_init(void *opaque)
 {
-	int ret;
-
 	if (!riscv_isa_extension_available(NULL, h)) {
 		kvm_info("hypervisor extension not available\n");
 		return -ENODEV;
 	}
=20
-	ret =3D kvm_riscv_setup_vsip();
-	if (ret)
-		return ret;
-
 	kvm_riscv_stage2_vmid_detect();
=20
 	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_c=
pu_context *cntx) {}
 				 riscv_isa_extension_mask(s) | \
 				 riscv_isa_extension_mask(u))
=20
-static unsigned long __percpu *vsip_shadow;
-
 static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu_csr *csr =3D &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 =3D &vcpu->arch.guest_csr;
-	unsigned long *vsip =3D raw_cpu_ptr(vsip_shadow);
=20
 	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 =3D csr->vsip;
 	csr_write(CSR_VSATP, csr->vsatp);
=20
 	kvm_riscv_stage2_update_hgatp(vcpu);
@@ -843,26 +839,8 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_v=
cpu *vcpu)
 static void kvm_riscv_update_vsip(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu_csr *csr =3D &vcpu->arch.guest_csr;
-	unsigned long *vsip =3D raw_cpu_ptr(vsip_shadow);
-
-	if (*vsip !=3D csr->vsip) {
-		csr_write(CSR_VSIP, csr->vsip);
-		*vsip =3D csr->vsip;
-	}
-}
-
-int kvm_riscv_setup_vsip(void)
-{
-	vsip_shadow =3D alloc_percpu(unsigned long);
-	if (!vsip_shadow)
-		return -ENOMEM;
=20
-	return 0;
-}
-
-void kvm_riscv_cleanup_vsip(void)
-{
-	free_percpu(vsip_shadow);
+	csr_write(CSR_VSIP, csr->vsip);
 }
=20
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
--=20
2.17.1