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target/arm/ptw: fix arm_cpu_get_phys_page_attrs_debug

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It was reported that QEMU monitor command gva2gpa was reporting unmapped
memory for a valid access (qemu-system-aarch64), during a copy from
kernel to user space (__arch_copy_to_user symbol in Linux) [1].
This was affecting cpu_memory_rw_debug also, which
is used in numerous places in our codebase. After investigating, the
problem was specific to arm_cpu_get_phys_page_attrs_debug.

When performing user access from a privileged space, we need to do a
second lookup for user mmu idx, following what get_a64_user_mem_index is
doing at translation time.

[1] https://lists.nongnu.org/archive/html/qemu-discuss/2025-04/msg00013.html

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-id: 20250414153027.1486719-5-pierrick.bouvier@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Pierrick Bouvier 2025-04-14 08:30:27 -07:00 • committed by Peter Maydell
parent 63201878f1
commit e1781b38af
1 changed files with 21 additions and 1 deletions
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22
target/arm/ptw.c
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@ -3656,5 +3656,25 @@ hwaddr arm_cpu_get_phys_page_attrs_debug(CPUState *cs, vaddr addr,
CPUARMState *env = &cpu->env;
ARMMMUIdx mmu_idx = arm_mmu_idx(env);
return arm_cpu_get_phys_page(env, addr, attrs, mmu_idx);
hwaddr res = arm_cpu_get_phys_page(env, addr, attrs, mmu_idx);
if (res != -1) {
return res;
}
/*
* Memory may be accessible for an "unprivileged load/store" variant.
* In this case, get_a64_user_mem_index function generates an op using an
* unprivileged mmu idx, so we need to try with it.
*/
switch (mmu_idx) {
case ARMMMUIdx_E10_1:
case ARMMMUIdx_E10_1_PAN:
return arm_cpu_get_phys_page(env, addr, attrs, ARMMMUIdx_E10_0);
case ARMMMUIdx_E20_2:
case ARMMMUIdx_E20_2_PAN:
return arm_cpu_get_phys_page(env, addr, attrs, ARMMMUIdx_E20_0);
default:
return -1;
}
}