linux-kernel - [PATCH v2 04/10] KVM: x86/mmu: Add Suppress VE bit to EPT shadow_mmio_mask/shadow_present

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Date: Tue, 16 Apr 2024 16:19:29 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: isaku.yamahata@...el.com,
	xiaoyao.li@...el.com,
	binbin.wu@...ux.intel.com,
	chao.gao@...el.com
Subject: [PATCH v2 04/10] KVM: x86/mmu: Add Suppress VE bit to EPT shadow_mmio_mask/shadow_present_mask

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>
Reviewed-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.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 4dba17363008..ac6da0a5f5e6 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -514,6 +514,7 @@ 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 768aaeddf5fa..0a0e83859c27 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -413,7 +413,9 @@ 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
@@ -430,7 +432,7 @@ 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);
 
-- 
2.43.0