This is a note to let you know that I've just added the patch titled
KVM: nVMX: fix HOST_CR3/HOST_CR4 cache
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-nvmx-fix-host_cr3-host_cr4-cache.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 44889942b6eb356eab27ce25fe10701adfec7776 Mon Sep 17 00:00:00 2001
From: Ladi Prosek <lprosek@xxxxxxxxxx>
Date: Fri, 22 Sep 2017 07:53:15 +0200
Subject: KVM: nVMX: fix HOST_CR3/HOST_CR4 cache
From: Ladi Prosek <lprosek@xxxxxxxxxx>
commit 44889942b6eb356eab27ce25fe10701adfec7776 upstream.
For nested virt we maintain multiple VMCS that can run on a vCPU. So it is
incorrect to keep vmcs_host_cr3 and vmcs_host_cr4, whose purpose is caching
the value of the rarely changing HOST_CR3 and HOST_CR4 VMCS fields, in
vCPU-wide data structures.
Hyper-V nested on KVM runs into this consistently for me with PCID enabled.
CR3 is updated with a new value, unlikely(cr3 != vmx->host_state.vmcs_host_cr3)
fires, and the currently loaded VMCS is updated. Then we switch from L2 to
L1 and the next exit reverts CR3 to its old value.
Fixes: d6e41f1151fe ("x86/mm, KVM: Teach KVM's VMX code that CR3 isn't a constant")
Signed-off-by: Ladi Prosek <lprosek@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -191,6 +191,8 @@ struct loaded_vmcs {
struct vmcs *shadow_vmcs;
int cpu;
int launched;
+ unsigned long vmcs_host_cr3; /* May not match real cr3 */
+ unsigned long vmcs_host_cr4; /* May not match real cr4 */
struct list_head loaded_vmcss_on_cpu_link;
};
@@ -573,8 +575,6 @@ struct vcpu_vmx {
int gs_ldt_reload_needed;
int fs_reload_needed;
u64 msr_host_bndcfgs;
- unsigned long vmcs_host_cr3; /* May not match real cr3 */
- unsigned long vmcs_host_cr4; /* May not match real cr4 */
} host_state;
struct {
int vm86_active;
@@ -4871,12 +4871,12 @@ static void vmx_set_constant_host_state(
*/
cr3 = read_cr3();
vmcs_writel(HOST_CR3, cr3); /* 22.2.3 FIXME: shadow tables */
- vmx->host_state.vmcs_host_cr3 = cr3;
+ vmx->loaded_vmcs->vmcs_host_cr3 = cr3;
/* Save the most likely value for this task's CR4 in the VMCS. */
cr4 = cr4_read_shadow();
vmcs_writel(HOST_CR4, cr4); /* 22.2.3, 22.2.5 */
- vmx->host_state.vmcs_host_cr4 = cr4;
+ vmx->loaded_vmcs->vmcs_host_cr4 = cr4;
vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS); /* 22.2.4 */
#ifdef CONFIG_X86_64
@@ -8874,15 +8874,15 @@ static void __noclone vmx_vcpu_run(struc
vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);
cr3 = __get_current_cr3_fast();
- if (unlikely(cr3 != vmx->host_state.vmcs_host_cr3)) {
+ if (unlikely(cr3 != vmx->loaded_vmcs->vmcs_host_cr3)) {
vmcs_writel(HOST_CR3, cr3);
- vmx->host_state.vmcs_host_cr3 = cr3;
+ vmx->loaded_vmcs->vmcs_host_cr3 = cr3;
}
cr4 = cr4_read_shadow();
- if (unlikely(cr4 != vmx->host_state.vmcs_host_cr4)) {
+ if (unlikely(cr4 != vmx->loaded_vmcs->vmcs_host_cr4)) {
vmcs_writel(HOST_CR4, cr4);
- vmx->host_state.vmcs_host_cr4 = cr4;
+ vmx->loaded_vmcs->vmcs_host_cr4 = cr4;
}
/* When single-stepping over STI and MOV SS, we must clear the
Patches currently in stable-queue which might be from lprosek@xxxxxxxxxx are
queue-4.9/kvm-nvmx-fix-host_cr3-host_cr4-cache.patch
queue-4.9/virtio-balloon-use-actual-number-of-stats-for-stats-queue-buffers.patch
queue-4.9/virtio_balloon-prevent-uninitialized-variable-use.patch