Re: [PATCH v8 4/6] LoongArch: KVM: Add vcpu search support from physical cpuid
From: maobibo
Date: Mon May 06 2024 - 05:35:36 EST
On 2024/5/6 下午4:59, Huacai Chen wrote:
On Mon, May 6, 2024 at 4:18 PM maobibo <maobibo@xxxxxxxxxxx> wrote:
On 2024/5/6 下午3:06, Huacai Chen wrote:
Hi, Bibo,
On Mon, May 6, 2024 at 2:36 PM maobibo <maobibo@xxxxxxxxxxx> wrote:
On 2024/5/6 上午9:49, Huacai Chen wrote:
Hi, Bibo,
On Sun, Apr 28, 2024 at 6:05 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
Physical cpuid is used for interrupt routing for irqchips such as
ipi/msi/extioi interrupt controller. And physical cpuid is stored
at CSR register LOONGARCH_CSR_CPUID, it can not be changed once vcpu
is created and physical cpuid of two vcpus cannot be the same.
Different irqchips have different size declaration about physical cpuid,
max cpuid value for CSR LOONGARCH_CSR_CPUID on 3A5000 is 512, max cpuid
supported by IPI hardware is 1024, 256 for extioi irqchip, and 65536
for MSI irqchip.
The smallest value from all interrupt controllers is selected now,
and the max cpuid size is defines as 256 by KVM which comes from
extioi irqchip.
Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
arch/loongarch/include/asm/kvm_host.h | 26 ++++++++
arch/loongarch/include/asm/kvm_vcpu.h | 1 +
arch/loongarch/kvm/vcpu.c | 93 ++++++++++++++++++++++++++-
arch/loongarch/kvm/vm.c | 11 ++++
4 files changed, 130 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index 2d62f7b0d377..3ba16ef1fe69 100644
--- a/arch/loongarch/include/asm/kvm_host.h
+++ b/arch/loongarch/include/asm/kvm_host.h
@@ -64,6 +64,30 @@ struct kvm_world_switch {
#define MAX_PGTABLE_LEVELS 4
+/*
+ * Physical cpu id is used for interrupt routing, there are different
+ * definitions about physical cpuid on different hardwares.
+ * For LOONGARCH_CSR_CPUID register, max cpuid size if 512
+ * For IPI HW, max dest CPUID size 1024
+ * For extioi interrupt controller, max dest CPUID size is 256
+ * For MSI interrupt controller, max supported CPUID size is 65536
+ *
+ * Currently max CPUID is defined as 256 for KVM hypervisor, in future
+ * it will be expanded to 4096, including 16 packages at most. And every
+ * package supports at most 256 vcpus
+ */
+#define KVM_MAX_PHYID 256
+
+struct kvm_phyid_info {
+ struct kvm_vcpu *vcpu;
+ bool enabled;
+};
+
+struct kvm_phyid_map {
+ int max_phyid;
+ struct kvm_phyid_info phys_map[KVM_MAX_PHYID];
+};
+
struct kvm_arch {
/* Guest physical mm */
kvm_pte_t *pgd;
@@ -71,6 +95,8 @@ struct kvm_arch {
unsigned long invalid_ptes[MAX_PGTABLE_LEVELS];
unsigned int pte_shifts[MAX_PGTABLE_LEVELS];
unsigned int root_level;
+ spinlock_t phyid_map_lock;
+ struct kvm_phyid_map *phyid_map;
s64 time_offset;
struct kvm_context __percpu *vmcs;
diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
index 0cb4fdb8a9b5..9f53950959da 100644
--- a/arch/loongarch/include/asm/kvm_vcpu.h
+++ b/arch/loongarch/include/asm/kvm_vcpu.h
@@ -81,6 +81,7 @@ void kvm_save_timer(struct kvm_vcpu *vcpu);
void kvm_restore_timer(struct kvm_vcpu *vcpu);
int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq);
+struct kvm_vcpu *kvm_get_vcpu_by_cpuid(struct kvm *kvm, int cpuid);
/*
* Loongarch KVM guest interrupt handling
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 3a8779065f73..b633fd28b8db 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -274,6 +274,95 @@ static int _kvm_getcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 *val)
return 0;
}
+static inline int kvm_set_cpuid(struct kvm_vcpu *vcpu, u64 val)
+{
+ int cpuid;
+ struct loongarch_csrs *csr = vcpu->arch.csr;
+ struct kvm_phyid_map *map;
+
+ if (val >= KVM_MAX_PHYID)
+ return -EINVAL;
+
+ cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
+ map = vcpu->kvm->arch.phyid_map;
+ spin_lock(&vcpu->kvm->arch.phyid_map_lock);
+ if (map->phys_map[cpuid].enabled) {
+ /*
+ * Cpuid is already set before
+ * Forbid changing different cpuid at runtime
+ */
+ if (cpuid != val) {
+ /*
+ * Cpuid 0 is initial value for vcpu, maybe invalid
+ * unset value for vcpu
+ */
+ if (cpuid) {
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return -EINVAL;
+ }
+ } else {
+ /* Discard duplicated cpuid set */
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return 0;
+ }
+ }
I have changed the logic and comments when I apply, you can double
check whether it is correct.
I checkout the latest version, the modification in function
kvm_set_cpuid() is good for me.
Now the modified version is like this:
+ if (map->phys_map[cpuid].enabled) {
+ /* Discard duplicated CPUID set operation */
+ if (cpuid == val) {
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return 0;
+ }
+
+ /*
+ * CPUID is already set before
+ * Forbid changing different CPUID at runtime
+ * But CPUID 0 is the initial value for vcpu, so allow
+ * changing from 0 to others
+ */
+ if (cpuid) {
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return -EINVAL;
+ }
+ }
But I still doubt whether we should allow changing from 0 to others
while map->phys_map[cpuid].enabled is 1.
It is necessary since the default sw cpuid is zero :-( And we can
optimize it in later, such as set INVALID cpuid in function
kvm_arch_vcpu_create() and logic will be simple in function kvm_set_cpuid().
In my opinion, if a vcpu with a uninitialized default physid=0, then
map->phys_map[cpuid].enabled should be 0, then code won't come here.
And if a vcpu with a real physid=0, then map->phys_map[cpuid].enabled
is 1, but we shouldn't allow it to change physid in this case.
yes, that is actually a problem.
vcpu0 firstly set physid=0, and vcpu0 set physid=1 again is not allowed.
vcpu0 firstly set physid=0, and vcpu1 set physid=1 is allowed.
Huacai
Regards
Bibo Mao
Huacai
+
+ if (map->phys_map[val].enabled) {
+ /*
+ * New cpuid is already set with other vcpu
+ * Forbid sharing the same cpuid between different vcpus
+ */
+ if (map->phys_map[val].vcpu != vcpu) {
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return -EINVAL;
+ }
+
+ /* Discard duplicated cpuid set operation*/
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return 0;
+ }
+
+ kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, val);
+ map->phys_map[val].enabled = true;
+ map->phys_map[val].vcpu = vcpu;
+ if (map->max_phyid < val)
+ map->max_phyid = val;
+ spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
+ return 0;
+}
+
+struct kvm_vcpu *kvm_get_vcpu_by_cpuid(struct kvm *kvm, int cpuid)
+{
+ struct kvm_phyid_map *map;
+
+ if (cpuid >= KVM_MAX_PHYID)
+ return NULL;
+
+ map = kvm->arch.phyid_map;
+ if (map->phys_map[cpuid].enabled)
+ return map->phys_map[cpuid].vcpu;
+
+ return NULL;
+}
+
+static inline void kvm_drop_cpuid(struct kvm_vcpu *vcpu)
+{
+ int cpuid;
+ struct loongarch_csrs *csr = vcpu->arch.csr;
+ struct kvm_phyid_map *map;
+
+ map = vcpu->kvm->arch.phyid_map;
+ cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
+ if (cpuid >= KVM_MAX_PHYID)
+ return;
+
+ if (map->phys_map[cpuid].enabled) {
+ map->phys_map[cpuid].vcpu = NULL;
+ map->phys_map[cpuid].enabled = false;
+ kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, 0);
+ }
+}
While kvm_set_cpuid() is protected by a spinlock, do kvm_drop_cpuid()
and kvm_get_vcpu_by_cpuid() also need it?
It is good to me that spinlock is added in function kvm_drop_cpuid().
And thinks for the efforts.
Regards
Bibo Mao
+
static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
{
int ret = 0, gintc;
@@ -291,7 +380,8 @@ static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
kvm_set_sw_gcsr(csr, LOONGARCH_CSR_ESTAT, gintc);
return ret;
- }
+ } else if (id == LOONGARCH_CSR_CPUID)
+ return kvm_set_cpuid(vcpu, val);
kvm_write_sw_gcsr(csr, id, val);
@@ -943,6 +1033,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
hrtimer_cancel(&vcpu->arch.swtimer);
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
kfree(vcpu->arch.csr);
+ kvm_drop_cpuid(vcpu);
I think this line should be before the above kfree(), otherwise you
get a "use after free".
Huacai
/*
* If the vCPU is freed and reused as another vCPU, we don't want the
diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
index 0a37f6fa8f2d..6006a28653ad 100644
--- a/arch/loongarch/kvm/vm.c
+++ b/arch/loongarch/kvm/vm.c
@@ -30,6 +30,14 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
if (!kvm->arch.pgd)
return -ENOMEM;
+ kvm->arch.phyid_map = kvzalloc(sizeof(struct kvm_phyid_map),
+ GFP_KERNEL_ACCOUNT);
+ if (!kvm->arch.phyid_map) {
+ free_page((unsigned long)kvm->arch.pgd);
+ kvm->arch.pgd = NULL;
+ return -ENOMEM;
+ }
+
kvm_init_vmcs(kvm);
kvm->arch.gpa_size = BIT(cpu_vabits - 1);
kvm->arch.root_level = CONFIG_PGTABLE_LEVELS - 1;
@@ -44,6 +52,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
for (i = 0; i <= kvm->arch.root_level; i++)
kvm->arch.pte_shifts[i] = PAGE_SHIFT + i * (PAGE_SHIFT - 3);
+ spin_lock_init(&kvm->arch.phyid_map_lock);
return 0;
}
@@ -51,7 +60,9 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
{
kvm_destroy_vcpus(kvm);
free_page((unsigned long)kvm->arch.pgd);
+ kvfree(kvm->arch.phyid_map);
kvm->arch.pgd = NULL;
+ kvm->arch.phyid_map = NULL;
}
int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
--
2.39.3