* [PATCH] KVM: X86: Raise #GP when clearing CR0_PG in 64 bit mode
@ 2021-12-07 9:52 Lai Jiangshan
2021-12-09 17:55 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Lai Jiangshan @ 2021-12-07 9:52 UTC (permalink / raw)
To: linux-kernel, kvm, Paolo Bonzini
Cc: Lai Jiangshan, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Dave Hansen, x86, H. Peter Anvin
From: Lai Jiangshan <laijs@linux.alibaba.com>
In the SDM:
If the logical processor is in 64-bit mode or if CR4.PCIDE = 1, an
attempt to clear CR0.PG causes a general-protection exception (#GP).
Software should transition to compatibility mode and clear CR4.PCIDE
before attempting to disable paging.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/kvm/x86.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 00f5b2b82909..78c40ac3b197 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -906,7 +906,8 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
!load_pdptrs(vcpu, kvm_read_cr3(vcpu)))
return 1;
- if (!(cr0 & X86_CR0_PG) && kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE))
+ if (!(cr0 & X86_CR0_PG) &&
+ (is_64_bit_mode(vcpu) || kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE)))
return 1;
static_call(kvm_x86_set_cr0)(vcpu, cr0);
--
2.19.1.6.gb485710b
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: X86: Raise #GP when clearing CR0_PG in 64 bit mode
2021-12-07 9:52 [PATCH] KVM: X86: Raise #GP when clearing CR0_PG in 64 bit mode Lai Jiangshan
@ 2021-12-09 17:55 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2021-12-09 17:55 UTC (permalink / raw)
To: Lai Jiangshan, linux-kernel, kvm
Cc: Lai Jiangshan, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Dave Hansen, x86, H. Peter Anvin
On 12/7/21 10:52, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@linux.alibaba.com>
>
> In the SDM:
> If the logical processor is in 64-bit mode or if CR4.PCIDE = 1, an
> attempt to clear CR0.PG causes a general-protection exception (#GP).
> Software should transition to compatibility mode and clear CR4.PCIDE
> before attempting to disable paging.
>
> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> ---
> arch/x86/kvm/x86.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 00f5b2b82909..78c40ac3b197 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -906,7 +906,8 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> !load_pdptrs(vcpu, kvm_read_cr3(vcpu)))
> return 1;
>
> - if (!(cr0 & X86_CR0_PG) && kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE))
> + if (!(cr0 & X86_CR0_PG) &&
> + (is_64_bit_mode(vcpu) || kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE)))
> return 1;
>
> static_call(kvm_x86_set_cr0)(vcpu, cr0);
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 2+ messages in thread
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