Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On Sun, Feb 11, 2018 at 3:56 AM, Wanpeng Li wrote: > Writes 0 to cr3 can't be detected during vmentry checks by hardware. I never suggested otherwise. I was just trying to explain why you can't assume that the host CR3 field in the VMCS matches the host CR3 at the time of

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On Sun, Feb 11, 2018 at 3:56 AM, Wanpeng Li wrote: > Writes 0 to cr3 can't be detected during vmentry checks by hardware. I never suggested otherwise. I was just trying to explain why you can't assume that the host CR3 field in the VMCS matches the host CR3 at the time of VMLAUNCH. KVM is set

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-08 23:29 GMT+08:00 Jim Mattson : > Consider the following scenario: > > L1 has never successfully executed VMLAUNCH. It has written 0 to > vmcs12's host CR3 field using VMWRITE, but the current host CR3 value Writes 0 to cr3 can't be detected during vmentry checks by

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-08 23:29 GMT+08:00 Jim Mattson : > Consider the following scenario: > > L1 has never successfully executed VMLAUNCH. It has written 0 to > vmcs12's host CR3 field using VMWRITE, but the current host CR3 value Writes 0 to cr3 can't be detected during vmentry checks by hardware. > is

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On 08/02/2018 16:54, Jim Mattson wrote: > On Thu, Feb 8, 2018 at 7:29 AM, Jim Mattson wrote: >> Similarly, the correct L1 CR4 value should be in vmcs01's CR4 >> read shadow field. > Sorry; that's wrong. L1's CR4 value has to be reconstructed from the > vmcs01 guest CR4 field

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On 08/02/2018 16:54, Jim Mattson wrote: > On Thu, Feb 8, 2018 at 7:29 AM, Jim Mattson wrote: >> Similarly, the correct L1 CR4 value should be in vmcs01's CR4 >> read shadow field. > Sorry; that's wrong. L1's CR4 value has to be reconstructed from the > vmcs01 guest CR4 field and CR4 shadow field

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On Thu, Feb 8, 2018 at 7:29 AM, Jim Mattson wrote: > Similarly, the correct L1 CR4 value should be in vmcs01's CR4 > read shadow field. Sorry; that's wrong. L1's CR4 value has to be reconstructed from the vmcs01 guest CR4 field and CR4 shadow field using the cr4 guest/host

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On Thu, Feb 8, 2018 at 7:29 AM, Jim Mattson wrote: > Similarly, the correct L1 CR4 value should be in vmcs01's CR4 > read shadow field. Sorry; that's wrong. L1's CR4 value has to be reconstructed from the vmcs01 guest CR4 field and CR4 shadow field using the cr4 guest/host mask. But there is no

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

Consider the following scenario: L1 has never successfully executed VMLAUNCH. It has written 0 to vmcs12's host CR3 field using VMWRITE, but the current host CR3 value is actually 3e7000. It has written some illegal control field that the L0 KVM doesn't check itself, but defers to the hardware

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

Consider the following scenario: L1 has never successfully executed VMLAUNCH. It has written 0 to vmcs12's host CR3 field using VMWRITE, but the current host CR3 value is actually 3e7000. It has written some illegal control field that the L0 KVM doesn't check itself, but defers to the hardware

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-08 0:57 GMT+08:00 Jim Mattson : > vmcs12->host_cr[34] does not contain the up-to-date values when L1 is > running. L1 can vmwrite any values there. We know at this point that It will incur a vmexit to emulate L1 vmwrites vmcs12->host_cr[34] even if vmcs shadow is

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-08 0:57 GMT+08:00 Jim Mattson : > vmcs12->host_cr[34] does not contain the up-to-date values when L1 is > running. L1 can vmwrite any values there. We know at this point that It will incur a vmexit to emulate L1 vmwrites vmcs12->host_cr[34] even if vmcs shadow is enabled since host_cr[34]

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

vmcs12->host_cr[34] does not contain the up-to-date values when L1 is running. L1 can vmwrite any values there. We know at this point that they are legal (because we checked them), but that's about it. If the VMLAUNCH/VMRESUME of vmcs12 fails for "invalid control field," there is no VM-exit from

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

vmcs12->host_cr[34] does not contain the up-to-date values when L1 is running. L1 can vmwrite any values there. We know at this point that they are legal (because we checked them), but that's about it. If the VMLAUNCH/VMRESUME of vmcs12 fails for "invalid control field," there is no VM-exit from

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-07 0:58 GMT+08:00 Jim Mattson : > On Mon, Feb 5, 2018 at 4:57 PM, Wanpeng Li wrote: > >> This is effective one, what I restore in this patch is >> achitectural/guest visible. > > This patch doesn't "restore" the guest visible CR4 to its value at

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-07 0:58 GMT+08:00 Jim Mattson : > On Mon, Feb 5, 2018 at 4:57 PM, Wanpeng Li wrote: > >> This is effective one, what I restore in this patch is >> achitectural/guest visible. > > This patch doesn't "restore" the guest visible CR4 to its value at the > time of VMLAUNCH/VMRESUME. It loads a

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On Mon, Feb 5, 2018 at 4:57 PM, Wanpeng Li wrote: > This is effective one, what I restore in this patch is > achitectural/guest visible. This patch doesn't "restore" the guest visible CR4 to its value at the time of VMLAUNCH/VMRESUME. It loads a new CR4 value from the

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On Mon, Feb 5, 2018 at 4:57 PM, Wanpeng Li wrote: > This is effective one, what I restore in this patch is > achitectural/guest visible. This patch doesn't "restore" the guest visible CR4 to its value at the time of VMLAUNCH/VMRESUME. It loads a new CR4 value from the vmcs12. That behavior is

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-06 2:24 GMT+08:00 Jim Mattson : > [Resending as plain text] > > On Mon, Feb 5, 2018 at 10:21 AM Jim Mattson wrote: > >> This is incorrect. In the event of an early VM-entry failure (e.g. a >> VM-entry failure for "VM entry with invalid control

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

2018-02-06 2:24 GMT+08:00 Jim Mattson : > [Resending as plain text] > > On Mon, Feb 5, 2018 at 10:21 AM Jim Mattson wrote: > >> This is incorrect. In the event of an early VM-entry failure (e.g. a >> VM-entry failure for "VM entry with invalid control field(s)"), no host >> state should be loaded

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

[Resending as plain text] On Mon, Feb 5, 2018 at 10:21 AM Jim Mattson wrote: > This is incorrect. In the event of an early VM-entry failure (e.g. a > VM-entry failure for "VM entry with invalid control field(s)"), no host > state should be loaded from the VMCS12. Of course,

Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

[Resending as plain text] On Mon, Feb 5, 2018 at 10:21 AM Jim Mattson wrote: > This is incorrect. In the event of an early VM-entry failure (e.g. a > VM-entry failure for "VM entry with invalid control field(s)"), no host > state should be loaded from the VMCS12. Of course, no guest state

[PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

From: Wanpeng Li In L0, Haswell client host: nested_vmx_exit_reflected failed vm entry 7 WARNING: CPU: 6 PID: 6797 at kvm/arch/x86/kvm//vmx.c:6206 handle_desc+0x2d/0x40 [kvm_intel] CPU: 6 PID: 6797 Comm: qemu-system-x86 Tainted: GW OE4.15.0+ #4 RIP:

[PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

From: Wanpeng Li In L0, Haswell client host: nested_vmx_exit_reflected failed vm entry 7 WARNING: CPU: 6 PID: 6797 at kvm/arch/x86/kvm//vmx.c:6206 handle_desc+0x2d/0x40 [kvm_intel] CPU: 6 PID: 6797 Comm: qemu-system-x86 Tainted: GW OE4.15.0+ #4 RIP: 0010:handle_desc+0x2d/0x40