linux-kernel - [RFC 22/48] RISC-V: KVM: Implement vcpu load/put functions for CoVE guests

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Message-Id: <20230419221716.3603068-23-atishp@rivosinc.com>
Date:   Wed, 19 Apr 2023 15:16:50 -0700
From:   Atish Patra <atishp@...osinc.com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atishp@...osinc.com>,
        Rajnesh Kanwal <rkanwal@...osinc.com>,
        Alexandre Ghiti <alex@...ti.fr>,
        Andrew Jones <ajones@...tanamicro.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        Björn Töpel <bjorn@...osinc.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-coco@...ts.linux.dev, Dylan Reid <dylan@...osinc.com>,
        abrestic@...osinc.com, Samuel Ortiz <sameo@...osinc.com>,
        Christoph Hellwig <hch@...radead.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guo Ren <guoren@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
        Jiri Slaby <jirislaby@...nel.org>,
        kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, linux-riscv@...ts.infradead.org,
        Mayuresh Chitale <mchitale@...tanamicro.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Uladzislau Rezki <urezki@...il.com>
Subject: [RFC 22/48] RISC-V: KVM: Implement vcpu load/put functions for CoVE guests

The TSM takes care of most of the H extension CSR/fp save/restore
for any guest running in CoVE. It may choose to do the fp save/restore
lazily as well. The host has to do minimal operations such timer
save/restore and interrupt state restore during vcpu load/put.

Signed-off-by: Rajnesh Kanwal <rkanwal@...osinc.com>
Signed-off-by: Atish Patra <atishp@...osinc.com>
---
 arch/riscv/kvm/cove.c | 12 ++++++++++--
 arch/riscv/kvm/vcpu.c | 12 +++++++++++-
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/cove.c b/arch/riscv/kvm/cove.c
index 87fa04b..c93de9b 100644
--- a/arch/riscv/kvm/cove.c
+++ b/arch/riscv/kvm/cove.c
@@ -139,12 +139,20 @@ __always_inline bool kvm_riscv_cove_enabled(void)
 
 void kvm_riscv_cove_vcpu_load(struct kvm_vcpu *vcpu)
 {
-	/* TODO */
+	kvm_riscv_vcpu_timer_restore(vcpu);
 }
 
 void kvm_riscv_cove_vcpu_put(struct kvm_vcpu *vcpu)
 {
-	/* TODO */
+	void *nshmem;
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	kvm_riscv_vcpu_timer_save(vcpu);
+	/* NACL is mandatory for CoVE */
+	nshmem = nacl_shmem();
+
+	/* Only VSIE needs to be read to manage the interrupt stuff */
+	csr->vsie = nacl_shmem_csr_read(nshmem, CSR_VSIE);
 }
 
 int kvm_riscv_cove_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 8cf462c..3e04b78 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -972,6 +972,11 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	u64 henvcfg = kvm_riscv_vcpu_get_henvcfg(vcpu->arch.isa);
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
 
+	if (is_cove_vcpu(vcpu)) {
+		kvm_riscv_cove_vcpu_load(vcpu);
+		goto skip_load;
+	}
+
 	if (kvm_riscv_nacl_sync_csr_available()) {
 		nshmem = nacl_shmem();
 		nacl_shmem_csr_write(nshmem, CSR_VSSTATUS, csr->vsstatus);
@@ -1010,9 +1015,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	kvm_riscv_vcpu_host_fp_save(&vcpu->arch.host_context);
 	kvm_riscv_vcpu_guest_fp_restore(&vcpu->arch.guest_context,
 					vcpu->arch.isa);
-
 	kvm_riscv_vcpu_aia_load(vcpu, cpu);
 
+skip_load:
 	vcpu->cpu = cpu;
 }
 
@@ -1023,6 +1028,11 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 
 	vcpu->cpu = -1;
 
+	if (is_cove_vcpu(vcpu)) {
+		kvm_riscv_cove_vcpu_put(vcpu);
+		return;
+	}
+
 	kvm_riscv_vcpu_aia_put(vcpu);
 
 	kvm_riscv_vcpu_guest_fp_save(&vcpu->arch.guest_context,
-- 
2.25.1