[RFC PATCH 18/73] KVM: x86/PVM: Implement VM/VCPU initialization related callbacks

Lai Jiangshan
2024-02-26T14:35:37Z

In the vm_init() callback, the cloned host root page table is recorded
into the 'kvm' structure, allowing for the cloning of host PGD entries
during SP allocation. In the vcpu_create() callback, the pfn cache for
'PVCS' is initialized and deactivated in the vcpu_free() callback.
Additionally, the vcpu_reset() callback needs to perform a common x86
reset and specific PVM reset.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
arch/x86/kvm/pvm/pvm.c | 120 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/pvm/pvm.h | 34 ++++++++++++
2 files changed, 154 insertions(+)

diff --git a/arch/x86/kvm/pvm/pvm.c b/arch/x86/kvm/pvm/pvm.c
index 83aa2c9f42f6..d4cc52bf6b3f 100644
--- a/arch/x86/kvm/pvm/pvm.c
+++ b/arch/x86/kvm/pvm/pvm.c
@@ -55,6 +55,117 @@ static bool cpu_has_pvm_wbinvd_exit(void)
return true;
}

+static void reset_segment(struct kvm_segment *var, int seg)
+{
+ memset(var, 0, sizeof(*var));
+ var->limit = 0xffff;
+ var->present = 1;
+
+ switch (seg) {
+ case VCPU_SREG_CS:
+ var->s = 1;
+ var->type = 0xb; /* Code Segment */
+ var->selector = 0xf000;
+ var->base = 0xffff0000;
+ break;
+ case VCPU_SREG_LDTR:
+ var->s = 0;
+ var->type = DESC_LDT;
+ break;
+ case VCPU_SREG_TR:
+ var->s = 0;
+ var->type = DESC_TSS | 0x2; // TSS32 busy
+ break;
+ default:
+ var->s = 1;
+ var->type = 3; /* Read/Write Data Segment */
+ break;
+ }
+}
+
+static void __pvm_vcpu_reset(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_pvm *pvm = to_pvm(vcpu);
+
+ if (is_intel)
+ vcpu->arch.microcode_version = 0x100000000ULL;
+ else
+ vcpu->arch.microcode_version = 0x01000065;
+
+ pvm->msr_ia32_feature_control_valid_bits = FEAT_CTL_LOCKED;
+}
+
+static void pvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
+{
+ struct vcpu_pvm *pvm = to_pvm(vcpu);
+ int i;
+
+ kvm_gpc_deactivate(&pvm->pvcs_gpc);
+
+ if (!init_event)
+ __pvm_vcpu_reset(vcpu);
+
+ /*
+ * For PVM, cpuid faulting relies on hardware capability, but it is set
+ * as supported by default in kvm_arch_vcpu_create(). Therefore, it
+ * should be cleared if the host doesn't support it.
+ */
+ if (!boot_cpu_has(X86_FEATURE_CPUID_FAULT))
+ vcpu->arch.msr_platform_info &= ~MSR_PLATFORM_INFO_CPUID_FAULT;
+
+ // X86 resets
+ for (i = 0; i < ARRAY_SIZE(pvm->segments); i++)
+ reset_segment(&pvm->segments[i], i);
+ kvm_set_cr8(vcpu, 0);
+ pvm->idt_ptr.address = 0;
+ pvm->idt_ptr.size = 0xffff;
+ pvm->gdt_ptr.address = 0;
+ pvm->gdt_ptr.size = 0xffff;
+
+ // PVM resets
+ pvm->switch_flags = SWITCH_FLAGS_INIT;
+ pvm->hw_cs = __USER_CS;
+ pvm->hw_ss = __USER_DS;
+ pvm->int_shadow = 0;
+ pvm->nmi_mask = false;
+
+ pvm->msr_vcpu_struct = 0;
+ pvm->msr_supervisor_rsp = 0;
+ pvm->msr_event_entry = 0;
+ pvm->msr_retu_rip_plus2 = 0;
+ pvm->msr_rets_rip_plus2 = 0;
+ pvm->msr_switch_cr3 = 0;
+}
+
+static int pvm_vcpu_create(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_pvm *pvm = to_pvm(vcpu);
+
+ BUILD_BUG_ON(offsetof(struct vcpu_pvm, vcpu) != 0);
+
+ pvm->switch_flags = SWITCH_FLAGS_INIT;
+ kvm_gpc_init(&pvm->pvcs_gpc, vcpu->kvm, vcpu, KVM_GUEST_AND_HOST_USE_PFN);
+
+ return 0;
+}
+
+static void pvm_vcpu_free(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_pvm *pvm = to_pvm(vcpu);
+
+ kvm_gpc_deactivate(&pvm->pvcs_gpc);
+}
+
+static void pvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
+{
+}
+
+static int pvm_vm_init(struct kvm *kvm)
+{
+ kvm->arch.host_mmu_root_pgd = host_mmu_root_pgd;
+ return 0;
+}
+
static int hardware_enable(void)
{
/* Nothing to do */
@@ -169,6 +280,15 @@ static struct kvm_x86_ops pvm_x86_ops __initdata = {

.has_wbinvd_exit = cpu_has_pvm_wbinvd_exit,

+ .vm_size = sizeof(struct kvm_pvm),
+ .vm_init = pvm_vm_init,
+
+ .vcpu_create = pvm_vcpu_create,
+ .vcpu_free = pvm_vcpu_free,
+ .vcpu_reset = pvm_vcpu_reset,
+
+ .vcpu_after_set_cpuid = pvm_vcpu_after_set_cpuid,
+
.nested_ops = &pvm_nested_ops,

.setup_mce = pvm_setup_mce,
diff --git a/arch/x86/kvm/pvm/pvm.h b/arch/x86/kvm/pvm/pvm.h
index 6149cf5975a4..599bbbb284dc 100644
--- a/arch/x86/kvm/pvm/pvm.h
+++ b/arch/x86/kvm/pvm/pvm.h
@@ -3,6 +3,9 @@
#define __KVM_X86_PVM_H

#include <linux/kvm_host.h>
+#include <asm/switcher.h>
+
+#define SWITCH_FLAGS_INIT (SWITCH_FLAGS_SMOD)

#define PT_L4_SHIFT 39
#define PT_L4_SIZE (1UL << PT_L4_SHIFT)
@@ -24,6 +27,37 @@ int host_mmu_init(void);

struct vcpu_pvm {
struct kvm_vcpu vcpu;
+
+ unsigned long switch_flags;
+
+ u32 hw_cs, hw_ss;
+
+ int int_shadow;
+ bool nmi_mask;
+
+ struct gfn_to_pfn_cache pvcs_gpc;
+
+ /*
+ * Only bits masked by msr_ia32_feature_control_valid_bits can be set in
+ * msr_ia32_feature_control. FEAT_CTL_LOCKED is always included
+ * in msr_ia32_feature_control_valid_bits.
+ */
+ u64 msr_ia32_feature_control;
+ u64 msr_ia32_feature_control_valid_bits;
+
+ // PVM paravirt MSRs
+ unsigned long msr_vcpu_struct;
+ unsigned long msr_supervisor_rsp;
+ unsigned long msr_supervisor_redzone;
+ unsigned long msr_event_entry;
+ unsigned long msr_retu_rip_plus2;
+ unsigned long msr_rets_rip_plus2;
+ unsigned long msr_switch_cr3;
+ unsigned long msr_linear_address_range;
+
+ struct kvm_segment segments[NR_VCPU_SREG];
+ struct desc_ptr idt_ptr;
+ struct desc_ptr gdt_ptr;
};

struct kvm_pvm {
--
2.19.1.6.gb485710b