* Re: [PATCH] kvm: x86: Read PDPTEs on CR0.CD and CR0.NW changes
2020-07-07 22:36 [PATCH] kvm: x86: Read PDPTEs on CR0.CD and CR0.NW changes Jim Mattson
@ 2020-07-08 9:45 ` Paolo Bonzini
2020-08-12 1:34 ` Alex Williamson
1 sibling, 0 replies; 5+ messages in thread
From: Paolo Bonzini @ 2020-07-08 9:45 UTC (permalink / raw)
To: Jim Mattson, kvm; +Cc: Oliver Upton, Peter Shier
On 08/07/20 00:36, Jim Mattson wrote:
> According to the SDM, when PAE paging would be in use following a
> MOV-to-CR0 that modifies any of CR0.CD, CR0.NW, or CR0.PG, then the
> PDPTEs are loaded from the address in CR3. Previously, kvm only loaded
> the PDPTEs when PAE paging would be in use following a MOV-to-CR0 that
> modified CR0.PG.
>
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Peter Shier <pshier@google.com>
> ---
> arch/x86/kvm/x86.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 88c593f83b28..5a91c975487d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -775,6 +775,7 @@ EXPORT_SYMBOL_GPL(pdptrs_changed);
> int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> {
> unsigned long old_cr0 = kvm_read_cr0(vcpu);
> + unsigned long pdptr_bits = X86_CR0_CD | X86_CR0_NW | X86_CR0_PG;
> unsigned long update_bits = X86_CR0_PG | X86_CR0_WP;
>
> cr0 |= X86_CR0_ET;
> @@ -792,9 +793,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> if ((cr0 & X86_CR0_PG) && !(cr0 & X86_CR0_PE))
> return 1;
>
> - if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) {
> + if (cr0 & X86_CR0_PG) {
> #ifdef CONFIG_X86_64
> - if ((vcpu->arch.efer & EFER_LME)) {
> + if (!is_paging(vcpu) && (vcpu->arch.efer & EFER_LME)) {
> int cs_db, cs_l;
>
> if (!is_pae(vcpu))
> @@ -804,8 +805,8 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> return 1;
> } else
> #endif
> - if (is_pae(vcpu) && !load_pdptrs(vcpu, vcpu->arch.walk_mmu,
> - kvm_read_cr3(vcpu)))
> + if (is_pae(vcpu) && ((cr0 ^ old_cr0) & pdptr_bits) &&
> + !load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu)))
> return 1;
> }
>
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] kvm: x86: Read PDPTEs on CR0.CD and CR0.NW changes
2020-07-07 22:36 [PATCH] kvm: x86: Read PDPTEs on CR0.CD and CR0.NW changes Jim Mattson
2020-07-08 9:45 ` Paolo Bonzini
@ 2020-08-12 1:34 ` Alex Williamson
2020-08-12 2:45 ` Jim Mattson
1 sibling, 1 reply; 5+ messages in thread
From: Alex Williamson @ 2020-08-12 1:34 UTC (permalink / raw)
To: Jim Mattson; +Cc: kvm, Paolo Bonzini, Oliver Upton, Peter Shier, Laszlo Ersek
On Tue, 7 Jul 2020 15:36:30 -0700
Jim Mattson <jmattson@google.com> wrote:
> According to the SDM, when PAE paging would be in use following a
> MOV-to-CR0 that modifies any of CR0.CD, CR0.NW, or CR0.PG, then the
> PDPTEs are loaded from the address in CR3. Previously, kvm only loaded
> the PDPTEs when PAE paging would be in use following a MOV-to-CR0 that
> modified CR0.PG.
>
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Peter Shier <pshier@google.com>
> ---
I can't even boot the simplest edk2 VM with this commit:
qemu-system-x86-core-5.0.0-2.fc32.x86_64
edk2-ovmf-20200201stable-1.fc32.noarch
<domain type="kvm">
<name>vm1</name>
<uuid>5ef9bfbe-46d9-4760-97a9-1290d2751908</uuid>
<memory unit="KiB">1048576</memory>
<currentMemory unit="KiB">1048576</currentMemory>
<vcpu placement="static">1</vcpu>
<os>
<type arch="x86_64" machine="pc-i440fx-5.0">hvm</type>
<loader readonly="yes"
type="pflash">/usr/share/edk2/ovmf/OVMF_CODE.fd</loader>
<nvram>/var/lib/libvirt/qemu/nvram/vm1_VARS.fd</nvram> <boot
dev="network"/> </os>
<features>
<acpi/>
<apic/>
<vmport state="off"/>
</features>
<cpu mode="host-model" check="partial"/>
<clock offset="utc">
<timer name="rtc" tickpolicy="catchup"/>
<timer name="pit" tickpolicy="delay"/>
<timer name="hpet" present="no"/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled="no"/>
<suspend-to-disk enabled="no"/>
</pm>
<devices>
<emulator>/usr/bin/qemu-kvm</emulator>
<controller type="usb" index="0" model="ich9-ehci1">
<address type="pci" domain="0x0000" bus="0x00" slot="0x05"
function="0x7"/> </controller>
<controller type="usb" index="0" model="ich9-uhci1">
<master startport="0"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x05"
function="0x0" multifunction="on"/> </controller>
<controller type="usb" index="0" model="ich9-uhci2">
<master startport="2"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x05"
function="0x1"/> </controller>
<controller type="usb" index="0" model="ich9-uhci3">
<master startport="4"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x05"
function="0x2"/> </controller>
<controller type="pci" index="0" model="pci-root"/>
<interface type="direct">
<mac address="52:54:00:62:fe:f4"/>
<source dev="enp4s0" mode="bridge"/>
<model type="e1000"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03"
function="0x0"/> </interface>
<input type="mouse" bus="ps2"/>
<input type="keyboard" bus="ps2"/>
<graphics type="vnc" port="-1" autoport="yes">
<listen type="address"/>
</graphics>
<video>
<model type="vga" vram="16384" heads="1" primary="yes"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02"
function="0x0"/> </video>
<memballoon model="virtio">
<address type="pci" domain="0x0000" bus="0x00" slot="0x07"
function="0x0"/> </memballoon>
</devices>
</domain>
/usr/bin/qemu-kvm \
-name guest=vm1,debug-threads=on \
-S \
-object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-3-vm1/master-key.aes \
-blockdev '{"driver":"file","filename":"/usr/share/edk2/ovmf/OVMF_CODE.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"raw","file":"libvirt-pflash0-storage"}' \
-blockdev '{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/vm1_VARS.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"raw","file":"libvirt-pflash1-storage"}' \
-machine pc-i440fx-5.0,accel=kvm,usb=off,vmport=off,dump-guest-core=off,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format \
-cpu IvyBridge-IBRS,ss=on,vmx=on,pdcm=on,pcid=on,hypervisor=on,arat=on,tsc-adjust=on,umip=on,md-clear=on,stibp=on,arch-capabilities=on,ssbd=on,xsaveopt=on,ibpb=on,amd-ssbd=on,skip-l1dfl-vmentry=on,pschange-mc-no=on \
-m 1024 \
-overcommit mem-lock=off \
-smp 1,sockets=1,cores=1,threads=1 \
-uuid 5ef9bfbe-46d9-4760-97a9-1290d2751908 \
-no-user-config \
-nodefaults \
-chardev socket,id=charmonitor,fd=36,server,nowait \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=utc,driftfix=slew \
-global kvm-pit.lost_tick_policy=delay \
-no-hpet \
-no-shutdown \
-global PIIX4_PM.disable_s3=1 \
-global PIIX4_PM.disable_s4=1 \
-boot strict=on \
-device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 \
-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 \
-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 \
-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 \
-netdev tap,fd=38,id=hostnet0 \
-device e1000,netdev=hostnet0,id=net0,mac=52:54:00:62:fe:f4,bus=pci.0,addr=0x3,bootindex=1 \
-vnc 127.0.0.1:0 \
-device VGA,id=video0,vgamem_mb=16,bus=pci.0,addr=0x2 \
-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
-msg timestamp=on
The graphics display is never initialized. Found via bisect, reverting
d42e3fae6fae against 00e4db51259a resolve the issue. Thanks,
Alex
> arch/x86/kvm/x86.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 88c593f83b28..5a91c975487d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -775,6 +775,7 @@ EXPORT_SYMBOL_GPL(pdptrs_changed);
> int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> {
> unsigned long old_cr0 = kvm_read_cr0(vcpu);
> + unsigned long pdptr_bits = X86_CR0_CD | X86_CR0_NW | X86_CR0_PG;
> unsigned long update_bits = X86_CR0_PG | X86_CR0_WP;
>
> cr0 |= X86_CR0_ET;
> @@ -792,9 +793,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> if ((cr0 & X86_CR0_PG) && !(cr0 & X86_CR0_PE))
> return 1;
>
> - if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) {
> + if (cr0 & X86_CR0_PG) {
> #ifdef CONFIG_X86_64
> - if ((vcpu->arch.efer & EFER_LME)) {
> + if (!is_paging(vcpu) && (vcpu->arch.efer & EFER_LME)) {
> int cs_db, cs_l;
>
> if (!is_pae(vcpu))
> @@ -804,8 +805,8 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> return 1;
> } else
> #endif
> - if (is_pae(vcpu) && !load_pdptrs(vcpu, vcpu->arch.walk_mmu,
> - kvm_read_cr3(vcpu)))
> + if (is_pae(vcpu) && ((cr0 ^ old_cr0) & pdptr_bits) &&
> + !load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu)))
> return 1;
> }
>
^ permalink raw reply [flat|nested] 5+ messages in thread