A single guest with nested virtualization needs two VMIDs: one for the guest hypervisor (L1) and another for the nested guest (L2).
To support this, divide the VMID space into two equal parts when nested virtualization is enabled. Signed-off-by: Anup Patel <[email protected]> --- arch/riscv/include/asm/kvm_vmid.h | 1 + arch/riscv/kvm/main.c | 4 ++-- arch/riscv/kvm/tlb.c | 11 +++++++++-- arch/riscv/kvm/vmid.c | 33 ++++++++++++++++++++++++++++--- 4 files changed, 42 insertions(+), 7 deletions(-) diff --git a/arch/riscv/include/asm/kvm_vmid.h b/arch/riscv/include/asm/kvm_vmid.h index db61b0525a8d..3048e12a639c 100644 --- a/arch/riscv/include/asm/kvm_vmid.h +++ b/arch/riscv/include/asm/kvm_vmid.h @@ -19,6 +19,7 @@ struct kvm_vmid { void __init kvm_riscv_gstage_vmid_detect(void); unsigned long kvm_riscv_gstage_vmid_bits(void); +unsigned long kvm_riscv_gstage_nested_vmid(unsigned long vmid); int kvm_riscv_gstage_vmid_init(struct kvm *kvm); bool kvm_riscv_gstage_vmid_ver_changed(struct kvm_vmid *vmid); void kvm_riscv_gstage_vmid_update(struct kvm_vcpu *vcpu); diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c index 5b4bf972d242..28044eefda47 100644 --- a/arch/riscv/kvm/main.c +++ b/arch/riscv/kvm/main.c @@ -123,8 +123,6 @@ static int __init riscv_kvm_init(void) return -ENODEV; } - kvm_riscv_gstage_vmid_detect(); - rc = kvm_riscv_aia_init(); if (rc && rc != -ENODEV) { kvm_riscv_nacl_exit(); @@ -133,6 +131,8 @@ static int __init riscv_kvm_init(void) kvm_riscv_nested_init(); + kvm_riscv_gstage_vmid_detect(); + kvm_info("hypervisor extension available\n"); if (kvm_riscv_nacl_available()) { diff --git a/arch/riscv/kvm/tlb.c b/arch/riscv/kvm/tlb.c index ff1aeac4eb8e..a95aa5336560 100644 --- a/arch/riscv/kvm/tlb.c +++ b/arch/riscv/kvm/tlb.c @@ -160,7 +160,7 @@ void kvm_riscv_local_hfence_vvma_all(unsigned long vmid) void kvm_riscv_local_tlb_sanitize(struct kvm_vcpu *vcpu) { - unsigned long vmid; + unsigned long vmid, nvmid; if (!kvm_riscv_gstage_vmid_bits() || vcpu->arch.last_exit_cpu == vcpu->cpu) @@ -180,12 +180,19 @@ void kvm_riscv_local_tlb_sanitize(struct kvm_vcpu *vcpu) vmid = READ_ONCE(vcpu->kvm->arch.vmid.vmid); kvm_riscv_local_hfence_gvma_vmid_all(vmid); + nvmid = kvm_riscv_gstage_nested_vmid(vmid); + if (vmid != nvmid) + kvm_riscv_local_hfence_gvma_vmid_all(nvmid); + /* * Flush VS-stage TLB entries for implementation where VS-stage * TLB does not cahce guest physical address and VMID. */ - if (static_branch_unlikely(&kvm_riscv_vsstage_tlb_no_gpa)) + if (static_branch_unlikely(&kvm_riscv_vsstage_tlb_no_gpa)) { kvm_riscv_local_hfence_vvma_all(vmid); + if (vmid != nvmid) + kvm_riscv_local_hfence_vvma_all(nvmid); + } } void kvm_riscv_fence_i_process(struct kvm_vcpu *vcpu) diff --git a/arch/riscv/kvm/vmid.c b/arch/riscv/kvm/vmid.c index cf34d448289d..2ddd95fe2d9c 100644 --- a/arch/riscv/kvm/vmid.c +++ b/arch/riscv/kvm/vmid.c @@ -25,6 +25,8 @@ static DEFINE_SPINLOCK(vmid_lock); void __init kvm_riscv_gstage_vmid_detect(void) { + unsigned long min_vmids; + /* Figure-out number of VMID bits in HW */ csr_write(CSR_HGATP, (kvm_riscv_gstage_mode << HGATP_MODE_SHIFT) | HGATP_VMID); vmid_bits = csr_read(CSR_HGATP); @@ -35,8 +37,23 @@ void __init kvm_riscv_gstage_vmid_detect(void) /* We polluted local TLB so flush all guest TLB */ kvm_riscv_local_hfence_gvma_all(); - /* We don't use VMID bits if they are not sufficient */ - if ((1UL << vmid_bits) < num_possible_cpus()) + /* + * A single guest with nested virtualization needs two + * VMIDs: one for the guest hypervisor (L1) and another + * for the nested guest (L2). + * + * Potentially, we can have a separate guest running on + * each host CPU so the number of VMIDs should not be: + * + * 1. less than the number of host CPUs for + * nested virtualization disabled + * 2. less than twice the number of host CPUs for + * nested virtualization enabled + */ + min_vmids = num_possible_cpus(); + if (kvm_riscv_nested_available()) + min_vmids = min_vmids * 2; + if (BIT(vmid_bits) < min_vmids) vmid_bits = 0; } @@ -45,6 +62,13 @@ unsigned long kvm_riscv_gstage_vmid_bits(void) return vmid_bits; } +unsigned long kvm_riscv_gstage_nested_vmid(unsigned long vmid) +{ + if (kvm_riscv_nested_available()) + return vmid | BIT(vmid_bits - 1); + return vmid; +} + int kvm_riscv_gstage_vmid_init(struct kvm *kvm) { /* Mark the initial VMID and VMID version invalid */ @@ -112,7 +136,10 @@ void kvm_riscv_gstage_vmid_update(struct kvm_vcpu *vcpu) vmid->vmid = vmid_next; vmid_next++; - vmid_next &= (1 << vmid_bits) - 1; + if (kvm_riscv_nested_available()) + vmid_next &= BIT(vmid_bits - 1) - 1; + else + vmid_next &= BIT(vmid_bits) - 1; WRITE_ONCE(vmid->vmid_version, READ_ONCE(vmid_version)); -- 2.43.0
