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LoongArch: KVM: Remove PGD saving during VM context switch

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PGD table for primary mmu keeps unchanged once VM is created, it is not
necessary to save PGD table pointer during VM context switch. And it can
be acquired when VM is created.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Bibo Mao
2025-03-18 16:48:08 +08:00
committed by Huacai Chen
parent 1c405b4217
commit 062ac0cb83
4 changed files with 15 additions and 10 deletions
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3
arch/loongarch/include/asm/kvm_host.h
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@@ -176,6 +176,9 @@ struct kvm_vcpu_arch {
/* Pointers stored here for easy accessing from assembly code */
int (*handle_exit)(struct kvm_run *run, struct kvm_vcpu *vcpu);
/* GPA (=HVA) of PGD for secondary mmu */
unsigned long kvm_pgd;
/* Host registers preserved across guest mode execution */
unsigned long host_sp;
unsigned long host_tp;

1
arch/loongarch/kernel/asm-offsets.c
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@@ -296,6 +296,7 @@ static void __used output_kvm_defines(void)
OFFSET(KVM_ARCH_HSP, kvm_vcpu_arch, host_sp);
OFFSET(KVM_ARCH_HTP, kvm_vcpu_arch, host_tp);
OFFSET(KVM_ARCH_HPGD, kvm_vcpu_arch, host_pgd);
OFFSET(KVM_ARCH_KVMPGD, kvm_vcpu_arch, kvm_pgd);
OFFSET(KVM_ARCH_HANDLE_EXIT, kvm_vcpu_arch, handle_exit);
OFFSET(KVM_ARCH_HEENTRY, kvm_vcpu_arch, host_eentry);
OFFSET(KVM_ARCH_GEENTRY, kvm_vcpu_arch, guest_eentry);

12
arch/loongarch/kvm/switch.S
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@@ -60,16 +60,8 @@
ld.d t0, a2, KVM_ARCH_GPC
csrwr t0, LOONGARCH_CSR_ERA
/* Save host PGDL */
csrrd t0, LOONGARCH_CSR_PGDL
st.d t0, a2, KVM_ARCH_HPGD
/* Switch to kvm */
ld.d t1, a2, KVM_VCPU_KVM - KVM_VCPU_ARCH
/* Load guest PGDL */
li.w t0, KVM_GPGD
ldx.d t0, t1, t0
/* Load PGD for KVM hypervisor */
ld.d t0, a2, KVM_ARCH_KVMPGD
csrwr t0, LOONGARCH_CSR_PGDL
/* Mix GID and RID */

9
arch/loongarch/kvm/vcpu.c
View File

@@ -1462,6 +1462,15 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
hrtimer_init(&vcpu->arch.swtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
vcpu->arch.swtimer.function = kvm_swtimer_wakeup;
/* Get GPA (=HVA) of PGD for kvm hypervisor */
vcpu->arch.kvm_pgd = __pa(vcpu->kvm->arch.pgd);
/*
* Get PGD for primary mmu, virtual address is used since there is
* memory access after loading from CSR_PGD in tlb exception fast path.
*/
vcpu->arch.host_pgd = (unsigned long)vcpu->kvm->mm->pgd;
vcpu->arch.handle_exit = kvm_handle_exit;
vcpu->arch.guest_eentry = (unsigned long)kvm_loongarch_ops->exc_entry;
vcpu->arch.csr = kzalloc(sizeof(struct loongarch_csrs), GFP_KERNEL);