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Subject[RESEND][PATCH] kvm: x86: Do not handle MMIO request in fast_page_fault
Date
From: Changbin Du <changbin.du@intel.com>

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: ffff9b47f5286000 task.stack: ffffb18d03b28000
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 <changbin.du@intel.com>
---
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
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