On 8/19/24 00:40, Richard Henderson wrote:
The two limit_max variables represent size - 1, just like the encoding in the GDT, thus the 'old' access was off by one. Access the minimal size of the new tss: the complete tss contains the iopb, which may be a larger block than the access api expects, and irrelevant because the iopb is not accessed during the switch itself.Fixes: 8b131065080a ("target/i386/tcg: use X86Access for TSS access") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2511 Signed-off-by: Richard Henderson <richard.hender...@linaro.org> --- target/i386/tcg/seg_helper.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/target/i386/tcg/seg_helper.c b/target/i386/tcg/seg_helper.c index bab552cd53..3b8fd827e1 100644 --- a/target/i386/tcg/seg_helper.c +++ b/target/i386/tcg/seg_helper.c @@ -378,7 +378,7 @@ static int switch_tss_ra(CPUX86State *env, int tss_selector,/* X86Access avoids memory exceptions during the task switch */mmu_index = cpu_mmu_index_kernel(env); - access_prepare_mmu(&old, env, env->tr.base, old_tss_limit_max, + access_prepare_mmu(&old, env, env->tr.base, old_tss_limit_max + 1, MMU_DATA_STORE, mmu_index, retaddr);if (source == SWITCH_TSS_CALL) {@@ -386,7 +386,8 @@ static int switch_tss_ra(CPUX86State *env, int tss_selector, probe_access(env, tss_base, 2, MMU_DATA_STORE, mmu_index, retaddr); } - access_prepare_mmu(&new, env, tss_base, tss_limit, + /* While true tss_limit may be larger, we don't access the iopb here. */ + access_prepare_mmu(&new, env, tss_base, tss_limit_max + 1, MMU_DATA_LOAD, mmu_index, retaddr);/* save the current state in the old TSS */
Reviewed-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>
