[PATCH v4 18/25] KVM: arm64: Consolidate stage-2 initialisation into a single function

Will Deacon
2022-10-17T12:02:21Z

From: Quentin Perret <qperret@google.com>

The initialisation of guest stage-2 page-tables is currently split
across two functions: kvm_init_stage2_mmu() and kvm_arm_setup_stage2().
That is presumably for historical reasons as kvm_arm_setup_stage2()
originates from the (now defunct) KVM port for 32-bit Arm.

Simplify this code path by merging both functions into one, taking care
to map the 'struct kvm' into the hypervisor stage-1 early on in order to
simplify the failure path.

Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/kvm_arm.h | 2 +-
arch/arm64/include/asm/kvm_host.h | 2 --
arch/arm64/include/asm/kvm_mmu.h | 2 +-
arch/arm64/kvm/arm.c | 27 +++++++++++++--------------
arch/arm64/kvm/mmu.c | 27 ++++++++++++++++++++++++++-
arch/arm64/kvm/reset.c | 29 -----------------------------
6 files changed, 41 insertions(+), 48 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 8aa8492dafc0..89e63585dae4 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -135,7 +135,7 @@
* 40 bits wide (T0SZ = 24). Systems with a PARange smaller than 40 bits are
* not known to exist and will break with this configuration.
*
- * The VTCR_EL2 is configured per VM and is initialised in kvm_arm_setup_stage2().
+ * The VTCR_EL2 is configured per VM and is initialised in kvm_init_stage2_mmu.
*
* Note that when using 4K pages, we concatenate two first level page tables
* together. With 16K pages, we concatenate 16 first level page tables.
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 2ec268cc2031..3fa973237b90 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -991,8 +991,6 @@ int kvm_set_ipa_limit(void);
#define __KVM_HAVE_ARCH_VM_ALLOC
struct kvm *kvm_arch_alloc_vm(void);

-int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type);
-
static inline bool kvm_vm_is_protected(struct kvm *kvm)
{
return false;
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 7784081088e7..e4a7e6369499 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -166,7 +166,7 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
void free_hyp_pgds(void);

void stage2_unmap_vm(struct kvm *kvm);
-int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu);
+int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long type);
void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
phys_addr_t pa, unsigned long size, bool writable);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index d99e93e6ddf7..f78eefa02f6b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -139,28 +139,24 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
int ret;

- ret = kvm_arm_setup_stage2(kvm, type);
- if (ret)
- return ret;
-
- ret = kvm_init_stage2_mmu(kvm, &kvm->arch.mmu);
- if (ret)
- return ret;
-
ret = kvm_share_hyp(kvm, kvm + 1);
if (ret)
- goto out_free_stage2_pgd;
+ return ret;

ret = pkvm_init_host_vm(kvm);
if (ret)
- goto out_free_stage2_pgd;
+ goto err_unshare_kvm;

if (!zalloc_cpumask_var(&kvm->arch.supported_cpus, GFP_KERNEL)) {
ret = -ENOMEM;
- goto out_free_stage2_pgd;
+ goto err_unshare_kvm;
}
cpumask_copy(kvm->arch.supported_cpus, cpu_possible_mask);

+ ret = kvm_init_stage2_mmu(kvm, &kvm->arch.mmu, type);
+ if (ret)
+ goto err_free_cpumask;
+
kvm_vgic_early_init(kvm);

/* The maximum number of VCPUs is limited by the host's GIC model */
@@ -169,9 +165,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
set_default_spectre(kvm);
kvm_arm_init_hypercalls(kvm);

- return ret;
-out_free_stage2_pgd:
- kvm_free_stage2_pgd(&kvm->arch.mmu);
+ return 0;
+
+err_free_cpumask:
+ free_cpumask_var(kvm->arch.supported_cpus);
+err_unshare_kvm:
+ kvm_unshare_hyp(kvm, kvm + 1);
return ret;
}

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 8b52566d1cb9..43761d31f763 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -668,15 +668,40 @@ static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
* kvm_init_stage2_mmu - Initialise a S2 MMU structure
* @kvm: The pointer to the KVM structure
* @mmu: The pointer to the s2 MMU structure
+ * @type: The machine type of the virtual machine
*
* Allocates only the stage-2 HW PGD level table(s).
* Note we don't need locking here as this is only called when the VM is
* created, which can only be done once.
*/
-int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
+int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long type)
{
+ u32 kvm_ipa_limit = get_kvm_ipa_limit();
int cpu, err;
struct kvm_pgtable *pgt;
+ u64 mmfr0, mmfr1;
+ u32 phys_shift;
+
+ if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
+ return -EINVAL;
+
+ phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
+ if (phys_shift) {
+ if (phys_shift > kvm_ipa_limit ||
+ phys_shift < ARM64_MIN_PARANGE_BITS)
+ return -EINVAL;
+ } else {
+ phys_shift = KVM_PHYS_SHIFT;
+ if (phys_shift > kvm_ipa_limit) {
+ pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
+ current->comm);
+ return -EINVAL;
+ }
+ }
+
+ mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
+ mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
+ kvm->arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);

if (mmu->pgt != NULL) {
kvm_err("kvm_arch already initialized?\n");
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 5ae18472205a..e0267f672b8a 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -395,32 +395,3 @@ int kvm_set_ipa_limit(void)

return 0;
}
-
-int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
-{
- u64 mmfr0, mmfr1;
- u32 phys_shift;
-
- if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
- return -EINVAL;
-
- phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
- if (phys_shift) {
- if (phys_shift > kvm_ipa_limit ||
- phys_shift < ARM64_MIN_PARANGE_BITS)
- return -EINVAL;
- } else {
- phys_shift = KVM_PHYS_SHIFT;
- if (phys_shift > kvm_ipa_limit) {
- pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
- current->comm);
- return -EINVAL;
- }
- }
-
- mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
- mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
- kvm->arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);
-
- return 0;
-}
--
2.38.0.413.g74048e4d9e-goog