From a2edf57f510cce6a389cc14e58c6ad0a4296d6f9 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Sun, 24 May 2009 22:19:00 +0300 Subject: [PATCH] KVM: Fix PDPTR reloading on CR4 writes The processor is documented to reload the PDPTRs while in PAE mode if any of the CR4 bits PSE, PGE, or PAE change. Linux relies on this behaviour when zapping the low mappings of PAE kernels during boot. The code already handled changes to CR4.PAE; augment it to also notice changes to PSE and PGE. This triggered while booting an F11 PAE kernel; the futex initialization code runs before any CR3 reloads and writes to a NULL pointer; the futex subsystem ended up uninitialized, killing PI futexes and pulseaudio which uses them. Cc: stable@kernel.org Signed-off-by: Avi Kivity --- arch/x86/kvm/x86.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 49079a46687b..3944e917e794 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -338,6 +338,9 @@ EXPORT_SYMBOL_GPL(kvm_lmsw); void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { + unsigned long old_cr4 = vcpu->arch.cr4; + unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE; + if (cr4 & CR4_RESERVED_BITS) { printk(KERN_DEBUG "set_cr4: #GP, reserved bits\n"); kvm_inject_gp(vcpu, 0); @@ -351,7 +354,8 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) kvm_inject_gp(vcpu, 0); return; } - } else if (is_paging(vcpu) && !is_pae(vcpu) && (cr4 & X86_CR4_PAE) + } else if (is_paging(vcpu) && (cr4 & X86_CR4_PAE) + && ((cr4 ^ old_cr4) & pdptr_bits) && !load_pdptrs(vcpu, vcpu->arch.cr3)) { printk(KERN_DEBUG "set_cr4: #GP, pdptrs reserved bits\n"); kvm_inject_gp(vcpu, 0); -- 2.20.1