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[PATCH 1/5] target/i386: mask high bits of CR3 in 32-bit mode


From: Paolo Bonzini
Subject: [PATCH 1/5] target/i386: mask high bits of CR3 in 32-bit mode
Date: Fri, 22 Dec 2023 18:59:47 +0100

CR3 bits 63:32 are ignored in 32-bit mode (either legacy 2-level
paging or PAE paging).  Do this in mmu_translate() to remove
the last where get_physical_address() meaningfully drops the high
bits of the address.

Cc: qemu-stable@nongnu.org
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Fixes: 4a1e9d4d11c ("target/i386: Use atomic operations for pte updates", 
2022-10-18)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/sysemu/excp_helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/i386/tcg/sysemu/excp_helper.c 
b/target/i386/tcg/sysemu/excp_helper.c
index 5b86f439add..11126c860d4 100644
--- a/target/i386/tcg/sysemu/excp_helper.c
+++ b/target/i386/tcg/sysemu/excp_helper.c
@@ -238,7 +238,7 @@ static bool mmu_translate(CPUX86State *env, const 
TranslateParams *in,
             /*
              * Page table level 3
              */
-            pte_addr = ((in->cr3 & ~0x1f) + ((addr >> 27) & 0x18)) & a20_mask;
+            pte_addr = ((in->cr3 & 0xffffffe0ULL) + ((addr >> 27) & 0x18)) & 
a20_mask;
             if (!ptw_translate(&pte_trans, pte_addr)) {
                 return false;
             }
@@ -306,7 +306,7 @@ static bool mmu_translate(CPUX86State *env, const 
TranslateParams *in,
         /*
          * Page table level 2
          */
-        pte_addr = ((in->cr3 & ~0xfff) + ((addr >> 20) & 0xffc)) & a20_mask;
+        pte_addr = ((in->cr3 & 0xfffff000ULL) + ((addr >> 20) & 0xffc)) & 
a20_mask;
         if (!ptw_translate(&pte_trans, pte_addr)) {
             return false;
         }
-- 
2.43.0




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