Re: [RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
On Wed, Sep 13, 2017 at 04:39:56PM +0200, Radim Krčmář wrote: > 2017-09-05 18:37+0800, changbin...@intel.com: > > From: Changbin Du> > > > If it is a MMIO request, it should be handled by slow path. This patch > > actually fixed below warning when mmu debug is enabled. > > > > WARNING: CPU: 5 PID: 2282 at arch/x86/kvm/mmu.c:226 > > fast_page_fault+0x41b/0x520 > > CPU: 5 PID: 2282 Comm: qemu-system-x86 Not tainted 4.13.0-rc6+ #34 > > task: 9b47f5286000 task.stack: b18d03b28000 > > RIP: 0010:fast_page_fault+0x41b/0x520 > > Call Trace: > > tdp_page_fault+0xfb/0x290 > > kvm_mmu_page_fault+0x61/0x120 > > handle_ept_misconfig+0x1ba/0x1c0 > > vmx_handle_exit+0xb8/0xd70 > > ? kvm_arch_vcpu_ioctl_run+0x9b6/0x18e0 > > kvm_arch_vcpu_ioctl_run+0xa5a/0x18e0 > > ? kvm_arch_vcpu_load+0x62/0x230 > > kvm_vcpu_ioctl+0x340/0x6c0 > > ? kvm_vcpu_ioctl+0x340/0x6c0 > > ? lock_acquire+0xf5/0x1f0 > > do_vfs_ioctl+0xa2/0x670 > > ? __fget+0x107/0x200 > > SyS_ioctl+0x79/0x90 > > entry_SYSCALL_64_fastpath+0x23/0xc2 > > > > Signed-off-by: Changbin Du > > --- > > arch/x86/kvm/mmu.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > > index 9d3f275..63c3360 100644 > > --- a/arch/x86/kvm/mmu.c > > +++ b/arch/x86/kvm/mmu.c > > @@ -3180,6 +3180,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, > > gva_t gva, int level, > > iterator.level < level) > > break; > > > > + if (is_mmio_spte(spte)) > > + break; > > Hm, handle_ept_misconfig() calls kvm_mmu_page_fault with error_code = > PFERR_RSVD_MASK. This error_code gets propagated and checked at the > beginning of page_fault_can_be_fast(), where it should break the > function execution. > > How did the execution get all the way to the loop? > hmm, a recent Paolo's cleanup patch already fixed it. e08d26f ("KVM: x86: simplify ept_misconfig") In the past, PFERR_RSVD_MASK is not set. So this patch doesnt need any more. thanks. > Thanks. -- Thanks, Changbin Du signature.asc Description: PGP signature
Re: [RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
On Wed, Sep 13, 2017 at 04:39:56PM +0200, Radim Krčmář wrote: > 2017-09-05 18:37+0800, changbin...@intel.com: > > From: Changbin Du > > > > If it is a MMIO request, it should be handled by slow path. This patch > > actually fixed below warning when mmu debug is enabled. > > > > WARNING: CPU: 5 PID: 2282 at arch/x86/kvm/mmu.c:226 > > fast_page_fault+0x41b/0x520 > > CPU: 5 PID: 2282 Comm: qemu-system-x86 Not tainted 4.13.0-rc6+ #34 > > task: 9b47f5286000 task.stack: b18d03b28000 > > RIP: 0010:fast_page_fault+0x41b/0x520 > > Call Trace: > > tdp_page_fault+0xfb/0x290 > > kvm_mmu_page_fault+0x61/0x120 > > handle_ept_misconfig+0x1ba/0x1c0 > > vmx_handle_exit+0xb8/0xd70 > > ? kvm_arch_vcpu_ioctl_run+0x9b6/0x18e0 > > kvm_arch_vcpu_ioctl_run+0xa5a/0x18e0 > > ? kvm_arch_vcpu_load+0x62/0x230 > > kvm_vcpu_ioctl+0x340/0x6c0 > > ? kvm_vcpu_ioctl+0x340/0x6c0 > > ? lock_acquire+0xf5/0x1f0 > > do_vfs_ioctl+0xa2/0x670 > > ? __fget+0x107/0x200 > > SyS_ioctl+0x79/0x90 > > entry_SYSCALL_64_fastpath+0x23/0xc2 > > > > Signed-off-by: Changbin Du > > --- > > arch/x86/kvm/mmu.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > > index 9d3f275..63c3360 100644 > > --- a/arch/x86/kvm/mmu.c > > +++ b/arch/x86/kvm/mmu.c > > @@ -3180,6 +3180,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, > > gva_t gva, int level, > > iterator.level < level) > > break; > > > > + if (is_mmio_spte(spte)) > > + break; > > Hm, handle_ept_misconfig() calls kvm_mmu_page_fault with error_code = > PFERR_RSVD_MASK. This error_code gets propagated and checked at the > beginning of page_fault_can_be_fast(), where it should break the > function execution. > > How did the execution get all the way to the loop? > hmm, a recent Paolo's cleanup patch already fixed it. e08d26f ("KVM: x86: simplify ept_misconfig") In the past, PFERR_RSVD_MASK is not set. So this patch doesnt need any more. thanks. > Thanks. -- Thanks, Changbin Du signature.asc Description: PGP signature
Re: [RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
2017-09-05 18:37+0800, changbin...@intel.com: > From: Changbin Du> > If it is a MMIO request, it should be handled by slow path. This patch > actually fixed below warning when mmu debug is enabled. > > WARNING: CPU: 5 PID: 2282 at arch/x86/kvm/mmu.c:226 > fast_page_fault+0x41b/0x520 > CPU: 5 PID: 2282 Comm: qemu-system-x86 Not tainted 4.13.0-rc6+ #34 > task: 9b47f5286000 task.stack: b18d03b28000 > RIP: 0010:fast_page_fault+0x41b/0x520 > Call Trace: > tdp_page_fault+0xfb/0x290 > kvm_mmu_page_fault+0x61/0x120 > handle_ept_misconfig+0x1ba/0x1c0 > vmx_handle_exit+0xb8/0xd70 > ? kvm_arch_vcpu_ioctl_run+0x9b6/0x18e0 > kvm_arch_vcpu_ioctl_run+0xa5a/0x18e0 > ? kvm_arch_vcpu_load+0x62/0x230 > kvm_vcpu_ioctl+0x340/0x6c0 > ? kvm_vcpu_ioctl+0x340/0x6c0 > ? lock_acquire+0xf5/0x1f0 > do_vfs_ioctl+0xa2/0x670 > ? __fget+0x107/0x200 > SyS_ioctl+0x79/0x90 > entry_SYSCALL_64_fastpath+0x23/0xc2 > > Signed-off-by: Changbin Du > --- > arch/x86/kvm/mmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 9d3f275..63c3360 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -3180,6 +3180,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, > gva_t gva, int level, > iterator.level < level) > break; > > + if (is_mmio_spte(spte)) > + break; Hm, handle_ept_misconfig() calls kvm_mmu_page_fault with error_code = PFERR_RSVD_MASK. This error_code gets propagated and checked at the beginning of page_fault_can_be_fast(), where it should break the function execution. How did the execution get all the way to the loop? Thanks.
Re: [RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
2017-09-05 18:37+0800, changbin...@intel.com: > From: Changbin Du > > If it is a MMIO request, it should be handled by slow path. This patch > actually fixed below warning when mmu debug is enabled. > > WARNING: CPU: 5 PID: 2282 at arch/x86/kvm/mmu.c:226 > fast_page_fault+0x41b/0x520 > CPU: 5 PID: 2282 Comm: qemu-system-x86 Not tainted 4.13.0-rc6+ #34 > task: 9b47f5286000 task.stack: b18d03b28000 > RIP: 0010:fast_page_fault+0x41b/0x520 > Call Trace: > tdp_page_fault+0xfb/0x290 > kvm_mmu_page_fault+0x61/0x120 > handle_ept_misconfig+0x1ba/0x1c0 > vmx_handle_exit+0xb8/0xd70 > ? kvm_arch_vcpu_ioctl_run+0x9b6/0x18e0 > kvm_arch_vcpu_ioctl_run+0xa5a/0x18e0 > ? kvm_arch_vcpu_load+0x62/0x230 > kvm_vcpu_ioctl+0x340/0x6c0 > ? kvm_vcpu_ioctl+0x340/0x6c0 > ? lock_acquire+0xf5/0x1f0 > do_vfs_ioctl+0xa2/0x670 > ? __fget+0x107/0x200 > SyS_ioctl+0x79/0x90 > entry_SYSCALL_64_fastpath+0x23/0xc2 > > Signed-off-by: Changbin Du > --- > arch/x86/kvm/mmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 9d3f275..63c3360 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -3180,6 +3180,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, > gva_t gva, int level, > iterator.level < level) > break; > > + if (is_mmio_spte(spte)) > + break; Hm, handle_ept_misconfig() calls kvm_mmu_page_fault with error_code = PFERR_RSVD_MASK. This error_code gets propagated and checked at the beginning of page_fault_can_be_fast(), where it should break the function execution. How did the execution get all the way to the loop? Thanks.
[RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
From: Changbin DuIf it is a MMIO request, it should be handled by slow path. This patch actually fixed below warning when mmu debug is enabled. WARNING: CPU: 5 PID: 2282 at arch/x86/kvm/mmu.c:226 fast_page_fault+0x41b/0x520 CPU: 5 PID: 2282 Comm: qemu-system-x86 Not tainted 4.13.0-rc6+ #34 task: 9b47f5286000 task.stack: b18d03b28000 RIP: 0010:fast_page_fault+0x41b/0x520 Call Trace: tdp_page_fault+0xfb/0x290 kvm_mmu_page_fault+0x61/0x120 handle_ept_misconfig+0x1ba/0x1c0 vmx_handle_exit+0xb8/0xd70 ? kvm_arch_vcpu_ioctl_run+0x9b6/0x18e0 kvm_arch_vcpu_ioctl_run+0xa5a/0x18e0 ? kvm_arch_vcpu_load+0x62/0x230 kvm_vcpu_ioctl+0x340/0x6c0 ? kvm_vcpu_ioctl+0x340/0x6c0 ? lock_acquire+0xf5/0x1f0 do_vfs_ioctl+0xa2/0x670 ? __fget+0x107/0x200 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x23/0xc2 Signed-off-by: Changbin Du --- arch/x86/kvm/mmu.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 9d3f275..63c3360 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3180,6 +3180,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level, iterator.level < level) break; + if (is_mmio_spte(spte)) + break; + sp = page_header(__pa(iterator.sptep)); if (!is_last_spte(spte, sp->role.level)) break; -- 2.7.4
[RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
From: Changbin Du If it is a MMIO request, it should be handled by slow path. This patch actually fixed below warning when mmu debug is enabled. WARNING: CPU: 5 PID: 2282 at arch/x86/kvm/mmu.c:226 fast_page_fault+0x41b/0x520 CPU: 5 PID: 2282 Comm: qemu-system-x86 Not tainted 4.13.0-rc6+ #34 task: 9b47f5286000 task.stack: b18d03b28000 RIP: 0010:fast_page_fault+0x41b/0x520 Call Trace: tdp_page_fault+0xfb/0x290 kvm_mmu_page_fault+0x61/0x120 handle_ept_misconfig+0x1ba/0x1c0 vmx_handle_exit+0xb8/0xd70 ? kvm_arch_vcpu_ioctl_run+0x9b6/0x18e0 kvm_arch_vcpu_ioctl_run+0xa5a/0x18e0 ? kvm_arch_vcpu_load+0x62/0x230 kvm_vcpu_ioctl+0x340/0x6c0 ? kvm_vcpu_ioctl+0x340/0x6c0 ? lock_acquire+0xf5/0x1f0 do_vfs_ioctl+0xa2/0x670 ? __fget+0x107/0x200 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x23/0xc2 Signed-off-by: Changbin Du --- arch/x86/kvm/mmu.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 9d3f275..63c3360 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3180,6 +3180,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level, iterator.level < level) break; + if (is_mmio_spte(spte)) + break; + sp = page_header(__pa(iterator.sptep)); if (!is_last_spte(spte, sp->role.level)) break; -- 2.7.4