From 72dc67a69690288538142df73a7e3ac66fea68dc Mon Sep 17 00:00:00 2001 From: Izik Eidus Date: Sun, 10 Feb 2008 18:04:15 +0200 Subject: KVM: remove the usage of the mmap_sem for the protection of the memory slots. This patch replaces the mmap_sem lock for the memory slots with a new kvm private lock, it is needed beacuse untill now there were cases where kvm accesses user memory while holding the mmap semaphore. Signed-off-by: Izik Eidus Signed-off-by: Avi Kivity --- arch/x86/kvm/vmx.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'arch/x86/kvm/vmx.c') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index ad36447e696e..86f5bf121838 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1477,7 +1477,7 @@ static int alloc_apic_access_page(struct kvm *kvm) struct kvm_userspace_memory_region kvm_userspace_mem; int r = 0; - down_write(¤t->mm->mmap_sem); + down_write(&kvm->slots_lock); if (kvm->arch.apic_access_page) goto out; kvm_userspace_mem.slot = APIC_ACCESS_PAGE_PRIVATE_MEMSLOT; @@ -1487,9 +1487,12 @@ static int alloc_apic_access_page(struct kvm *kvm) r = __kvm_set_memory_region(kvm, &kvm_userspace_mem, 0); if (r) goto out; + + down_read(¤t->mm->mmap_sem); kvm->arch.apic_access_page = gfn_to_page(kvm, 0xfee00); + up_read(¤t->mm->mmap_sem); out: - up_write(¤t->mm->mmap_sem); + up_write(&kvm->slots_lock); return r; } -- cgit v1.2.3 From 5e4a0b3c1b899bb0ba28bde6edf95c5ddeb48b5c Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Thu, 14 Feb 2008 21:21:43 -0200 Subject: KVM: move alloc_apic_access_page() outside of non-preemptable region alloc_apic_access_page() can sleep, while vmx_vcpu_setup is called inside a non preemptable region. Move it after put_cpu(). Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/vmx.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm/vmx.c') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 86f5bf121838..61c2a3a8d20a 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1605,9 +1605,6 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL); vmcs_writel(CR4_GUEST_HOST_MASK, KVM_GUEST_CR4_MASK); - if (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm)) - if (alloc_apic_access_page(vmx->vcpu.kvm) != 0) - return -ENOMEM; return 0; } @@ -2537,6 +2534,9 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) put_cpu(); if (err) goto free_vmcs; + if (vm_need_virtualize_apic_accesses(kvm)) + if (alloc_apic_access_page(kvm) != 0) + goto free_vmcs; return &vmx->vcpu; -- cgit v1.2.3 From 33f9c505ed5c83bd8a07877e5b4628308f4cc099 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 27 Feb 2008 16:06:57 +0200 Subject: KVM: VMX: Avoid rearranging switched guest msrs while they are loaded KVM tries to run as much as possible with the guest msrs loaded instead of host msrs, since switching msrs is very expensive. It also tries to minimize the number of msrs switched according to the guest mode; for example, MSR_LSTAR is needed only by long mode guests. This optimization is done by setup_msrs(). However, we must not change which msrs are switched while we are running with guest msr state: - switch to guest msr state - call setup_msrs(), removing some msrs from the list - switch to host msr state, leaving a few guest msrs loaded An easy way to trigger this is to kexec an x86_64 linux guest. Early during setup, the guest will switch EFER to not include SCE. KVM will stop saving MSR_LSTAR, and on the next msr switch it will leave the guest LSTAR loaded. The next host syscall will end up in a random location in the kernel. Fix by reloading the host msrs before changing the msr list. Signed-off-by: Avi Kivity --- arch/x86/kvm/vmx.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/kvm/vmx.c') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 61c2a3a8d20a..94ea724638fd 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -638,6 +638,7 @@ static void setup_msrs(struct vcpu_vmx *vmx) { int save_nmsrs; + vmx_load_host_state(vmx); save_nmsrs = 0; #ifdef CONFIG_X86_64 if (is_long_mode(&vmx->vcpu)) { -- cgit v1.2.3