From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> [ Upstream commit bf8036a4098d1548cdccf9ed5c523ef4e83e3c68 ] This patch fixes the below warning reported during migration: find_kvm_secondary_pte called with kvm mmu_lock not held CPU: 23 PID: 5341 Comm: qemu-system-ppc Tainted: G W 5.7.0-rc5-kvm-00211-g9ccf10d6d088 #432 NIP: c008000000fe848c LR: c008000000fe8488 CTR: 0000000000000000 REGS: c000001e19f077e0 TRAP: 0700 Tainted: G W (5.7.0-rc5-kvm-00211-g9ccf10d6d088) MSR: 9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 42222422 XER: 20040000 CFAR: c00000000012f5ac IRQMASK: 0 GPR00: c008000000fe8488 c000001e19f07a70 c008000000ffe200 0000000000000039 GPR04: 0000000000000001 c000001ffc8b4900 0000000000018840 0000000000000007 GPR08: 0000000000000003 0000000000000001 0000000000000007 0000000000000001 GPR12: 0000000000002000 c000001fff6d9400 000000011f884678 00007fff70b70000 GPR16: 00007fff7137cb90 00007fff7dcb4410 0000000000000001 0000000000000000 GPR20: 000000000ffe0000 0000000000000000 0000000000000001 0000000000000000 GPR24: 8000000000000000 0000000000000001 c000001e1f67e600 c000001e1fd82410 GPR28: 0000000000001000 c000001e2e410000 0000000000000fff 0000000000000ffe NIP [c008000000fe848c] kvmppc_hv_get_dirty_log_radix+0x2e4/0x340 [kvm_hv] LR [c008000000fe8488] kvmppc_hv_get_dirty_log_radix+0x2e0/0x340 [kvm_hv] Call Trace: [c000001e19f07a70] [c008000000fe8488] kvmppc_hv_get_dirty_log_radix+0x2e0/0x340 [kvm_hv] (unreliable) [c000001e19f07b50] [c008000000fd42e4] kvm_vm_ioctl_get_dirty_log_hv+0x33c/0x3c0 [kvm_hv] [c000001e19f07be0] [c008000000eea878] kvm_vm_ioctl_get_dirty_log+0x30/0x50 [kvm] [c000001e19f07c00] [c008000000edc818] kvm_vm_ioctl+0x2b0/0xc00 [kvm] [c000001e19f07d50] [c00000000046e148] ksys_ioctl+0xf8/0x150 [c000001e19f07da0] [c00000000046e1c8] sys_ioctl+0x28/0x80 [c000001e19f07dc0] [c00000000003652c] system_call_exception+0x16c/0x240 [c000001e19f07e20] [c00000000000d070] system_call_common+0xf0/0x278 Instruction dump: 7d3a512a 4200ffd0 7ffefb78 4bfffdc4 60000000 3c820000 e8848468 3c620000 e86384a8 38840010 4800673d e8410018 <0fe00000> 4bfffdd4 60000000 60000000 Reported-by: Paul Mackerras <paulus@xxxxxxxxxx> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20200528080456.87797-1-aneesh.kumar@xxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/powerpc/include/asm/kvm_book3s_64.h | 10 +++++++ arch/powerpc/kvm/book3s_64_mmu_radix.c | 35 ++++++++++++++++++++---- 2 files changed, 39 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index 2c2635967d6e0..0431db7b82af7 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -635,6 +635,16 @@ extern void kvmhv_remove_nest_rmap_range(struct kvm *kvm, unsigned long gpa, unsigned long hpa, unsigned long nbytes); +static inline pte_t * +find_kvm_secondary_pte_unlocked(struct kvm *kvm, unsigned long ea, + unsigned *hshift) +{ + pte_t *pte; + + pte = __find_linux_pte(kvm->arch.pgtable, ea, NULL, hshift); + return pte; +} + static inline pte_t *find_kvm_secondary_pte(struct kvm *kvm, unsigned long ea, unsigned *hshift) { diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index e9b3622405b1d..d4e532a63f08e 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -1052,7 +1052,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, { unsigned long gfn = memslot->base_gfn + pagenum; unsigned long gpa = gfn << PAGE_SHIFT; - pte_t *ptep; + pte_t *ptep, pte; unsigned int shift; int ret = 0; unsigned long old, *rmapp; @@ -1060,12 +1060,35 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE) return ret; - ptep = find_kvm_secondary_pte(kvm, gpa, &shift); - if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) { - ret = 1; - if (shift) - ret = 1 << (shift - PAGE_SHIFT); + /* + * For performance reasons we don't hold kvm->mmu_lock while walking the + * partition scoped table. + */ + ptep = find_kvm_secondary_pte_unlocked(kvm, gpa, &shift); + if (!ptep) + return 0; + + pte = READ_ONCE(*ptep); + if (pte_present(pte) && pte_dirty(pte)) { spin_lock(&kvm->mmu_lock); + /* + * Recheck the pte again + */ + if (pte_val(pte) != pte_val(*ptep)) { + /* + * We have KVM_MEM_LOG_DIRTY_PAGES enabled. Hence we can + * only find PAGE_SIZE pte entries here. We can continue + * to use the pte addr returned by above page table + * walk. + */ + if (!pte_present(*ptep) || !pte_dirty(*ptep)) { + spin_unlock(&kvm->mmu_lock); + return 0; + } + } + + ret = 1; + VM_BUG_ON(shift); old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_DIRTY, 0, gpa, shift); kvmppc_radix_tlbie_page(kvm, gpa, shift, kvm->arch.lpid); -- 2.25.1
