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Message-ID: <891c98f2-9300-4393-b3d1-ac975892bcb8@linux.intel.com>
Date: Tue, 5 Mar 2024 21:17:16 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, seanjc@...gle.com,
michael.roth@....com, isaku.yamahata@...el.com, thomas.lendacky@....com
Subject: Re: [PATCH 05/21] KVM: x86/mmu: Add Suppress VE bit to EPT
shadow_mmio_mask/shadow_present_mask
On 2/28/2024 7:20 AM, Paolo Bonzini wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
>
> To make use of the same value of shadow_mmio_mask and shadow_present_mask
> for TDX and VMX, add Suppress-VE bit to shadow_mmio_mask and
> shadow_present_mask so that they can be common for both VMX and TDX.
>
> TDX will require shadow_mmio_mask and shadow_present_mask to include
> VMX_SUPPRESS_VE for shared GPA so that EPT violation is triggered for
> shared GPA. For VMX, VMX_SUPPRESS_VE doesn't matter for MMIO because the
> spte value is defined so as to cause EPT misconfig.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Message-Id: <97cc616b3563cd8277be91aaeb3e14bce23c3649.1705965635.git.isaku.yamahata@...el.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>
> ---
> arch/x86/include/asm/vmx.h | 1 +
> arch/x86/kvm/mmu/spte.c | 6 ++++--
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index 0e73616b82f3..76ed39541a52 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -513,6 +513,7 @@ enum vmcs_field {
> #define VMX_EPT_IPAT_BIT (1ull << 6)
> #define VMX_EPT_ACCESS_BIT (1ull << 8)
> #define VMX_EPT_DIRTY_BIT (1ull << 9)
> +#define VMX_EPT_SUPPRESS_VE_BIT (1ull << 63)
> #define VMX_EPT_RWX_MASK (VMX_EPT_READABLE_MASK | \
> VMX_EPT_WRITABLE_MASK | \
> VMX_EPT_EXECUTABLE_MASK)
> diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
> index 4a599130e9c9..02a466de2991 100644
> --- a/arch/x86/kvm/mmu/spte.c
> +++ b/arch/x86/kvm/mmu/spte.c
> @@ -429,7 +429,9 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only)
> shadow_dirty_mask = has_ad_bits ? VMX_EPT_DIRTY_BIT : 0ull;
> shadow_nx_mask = 0ull;
> shadow_x_mask = VMX_EPT_EXECUTABLE_MASK;
> - shadow_present_mask = has_exec_only ? 0ull : VMX_EPT_READABLE_MASK;
> + /* VMX_EPT_SUPPRESS_VE_BIT is needed for W or X violation. */
> + shadow_present_mask =
> + (has_exec_only ? 0ull : VMX_EPT_READABLE_MASK) | VMX_EPT_SUPPRESS_VE_BIT;
> /*
> * EPT overrides the host MTRRs, and so KVM must program the desired
> * memtype directly into the SPTEs. Note, this mask is just the mask
> @@ -446,7 +448,7 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only)
> * of an EPT paging-structure entry is 110b (write/execute).
> */
> kvm_mmu_set_mmio_spte_mask(VMX_EPT_MISCONFIG_WX_VALUE,
> - VMX_EPT_RWX_MASK, 0);
> + VMX_EPT_RWX_MASK | VMX_EPT_SUPPRESS_VE_BIT, 0);
> }
> EXPORT_SYMBOL_GPL(kvm_mmu_set_ept_masks);
>
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