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[47.64.113.183]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45df81cbd55sm20854025e9.3.2025.09.10.02.07.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Sep 2025 02:07:17 -0700 (PDT) Message-ID: Date: Wed, 10 Sep 2025 11:07:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PULL 10/16] target/i386: implement TSS trap bit To: Mark Cave-Ayland , Paolo Bonzini , qemu-devel@nongnu.org References: <20250512190524.179419-1-pbonzini@redhat.com> <20250512190524.179419-11-pbonzini@redhat.com> <23d92164-5f1c-4905-a2c9-12ae2db580f5@redhat.com> From: Thomas Huth Content-Language: en-US Autocrypt: addr=thuth@redhat.com; keydata= xsFNBFH7eUwBEACzyOXKU+5Pcs6wNpKzrlJwzRl3VGZt95VCdb+FgoU9g11m7FWcOafrVRwU yYkTm9+7zBUc0sW5AuPGR/dp3pSLX/yFWsA/UB4nJsHqgDvDU7BImSeiTrnpMOTXb7Arw2a2 4CflIyFqjCpfDM4MuTmzTjXq4Uov1giGE9X6viNo1pxyEpd7PanlKNnf4PqEQp06X4IgUacW tSGj6Gcns1bCuHV8OPWLkf4hkRnu8hdL6i60Yxz4E6TqlrpxsfYwLXgEeswPHOA6Mn4Cso9O 0lewVYfFfsmokfAVMKWzOl1Sr0KGI5T9CpmRfAiSHpthhHWnECcJFwl72NTi6kUcUzG4se81 O6n9d/kTj7pzTmBdfwuOZ0YUSqcqs0W+l1NcASSYZQaDoD3/SLk+nqVeCBB4OnYOGhgmIHNW 0CwMRO/GK+20alxzk//V9GmIM2ACElbfF8+Uug3pqiHkVnKqM7W9/S1NH2qmxB6zMiJUHlTH gnVeZX0dgH27mzstcF786uPcdEqS0KJuxh2kk5IvUSL3Qn3ZgmgdxBMyCPciD/1cb7/Ahazr 3ThHQXSHXkH/aDXdfLsKVuwDzHLVSkdSnZdt5HHh75/NFHxwaTlydgfHmFFwodK8y/TjyiGZ zg2Kje38xnz8zKn9iesFBCcONXS7txENTzX0z80WKBhK+XSFJwARAQABzR5UaG9tYXMgSHV0 aCA8dGh1dGhAcmVkaGF0LmNvbT7CwXgEEwECACIFAlVgX6oCGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAAoJEC7Z13T+cC21EbIP/ii9cvT2HHGbFRl8HqGT6+7Wkb+XLMqJBMAIGiQK QIP3xk1HPTsLfVG0ao4hy/oYkGNOP8+ubLnZen6Yq3zAFiMhQ44lvgigDYJo3Ve59gfe99KX EbtB+X95ODARkq0McR6OAsPNJ7gpEUzfkQUUJTXRDQXfG/FX303Gvk+YU0spm2tsIKPl6AmV 1CegDljzjycyfJbk418MQmMu2T82kjrkEofUO2a24ed3VGC0/Uz//XCR2ZTo+vBoBUQl41BD eFFtoCSrzo3yPFS+w5fkH9NT8ChdpSlbNS32NhYQhJtr9zjWyFRf0Zk+T/1P7ECn6gTEkp5k ofFIA4MFBc/fXbaDRtBmPB0N9pqTFApIUI4vuFPPO0JDrII9dLwZ6lO9EKiwuVlvr1wwzsgq zJTPBU3qHaUO4d/8G+gD7AL/6T4zi8Jo/GmjBsnYaTzbm94lf0CjXjsOX3seMhaE6WAZOQQG tZHAO1kAPWpaxne+wtgMKthyPLNwelLf+xzGvrIKvLX6QuLoWMnWldu22z2ICVnLQChlR9d6 WW8QFEpo/FK7omuS8KvvopFcOOdlbFMM8Y/8vBgVMSsK6fsYUhruny/PahprPbYGiNIhKqz7 UvgyZVl4pBFjTaz/SbimTk210vIlkDyy1WuS8Zsn0htv4+jQPgo9rqFE4mipJjy/iboDzsFN BFH7eUwBEAC2nzfUeeI8dv0C4qrfCPze6NkryUflEut9WwHhfXCLjtvCjnoGqFelH/PE9NF4 4VPSCdvD1SSmFVzu6T9qWdcwMSaC+e7G/z0/AhBfqTeosAF5XvKQlAb9ZPkdDr7YN0a1XDfa +NgA+JZB4ROyBZFFAwNHT+HCnyzy0v9Sh3BgJJwfpXHH2l3LfncvV8rgFv0bvdr70U+On2XH 5bApOyW1WpIG5KPJlDdzcQTyptOJ1dnEHfwnABEfzI3dNf63rlxsGouX/NFRRRNqkdClQR3K gCwciaXfZ7ir7fF0u1N2UuLsWA8Ei1JrNypk+MRxhbvdQC4tyZCZ8mVDk+QOK6pyK2f4rMf/ WmqxNTtAVmNuZIwnJdjRMMSs4W4w6N/bRvpqtykSqx7VXcgqtv6eqoDZrNuhGbekQA0sAnCJ VPArerAZGArm63o39me/bRUQeQVSxEBmg66yshF9HkcUPGVeC4B0TPwz+HFcVhheo6hoJjLq knFOPLRj+0h+ZL+D0GenyqD3CyuyeTT5dGcNU9qT74bdSr20k/CklvI7S9yoQje8BeQAHtdV cvO8XCLrpGuw9SgOS7OP5oI26a0548M4KldAY+kqX6XVphEw3/6U1KTf7WxW5zYLTtadjISB X9xsRWSU+Yqs3C7oN5TIPSoj9tXMoxZkCIHWvnqGwZ7JhwARAQABwsFfBBgBAgAJBQJR+3lM AhsMAAoJEC7Z13T+cC21hPAQAIsBL9MdGpdEpvXs9CYrBkd6tS9mbaSWj6XBDfA1AEdQkBOn ZH1Qt7HJesk+qNSnLv6+jP4VwqK5AFMrKJ6IjE7jqgzGxtcZnvSjeDGPF1h2CKZQPpTw890k fy18AvgFHkVk2Oylyexw3aOBsXg6ukN44vIFqPoc+YSU0+0QIdYJp/XFsgWxnFIMYwDpxSHS 5fdDxUjsk3UBHZx+IhFjs2siVZi5wnHIqM7eK9abr2cK2weInTBwXwqVWjsXZ4tq5+jQrwDK cvxIcwXdUTLGxc4/Z/VRH1PZSvfQxdxMGmNTGaXVNfdFZjm4fz0mz+OUi6AHC4CZpwnsliGV ODqwX8Y1zic9viSTbKS01ZNp175POyWViUk9qisPZB7ypfSIVSEULrL347qY/hm9ahhqmn17 Ng255syASv3ehvX7iwWDfzXbA0/TVaqwa1YIkec+/8miicV0zMP9siRcYQkyTqSzaTFBBmqD oiT+z+/E59qj/EKfyce3sbC9XLjXv3mHMrq1tKX4G7IJGnS989E/fg6crv6NHae9Ckm7+lSs IQu4bBP2GxiRQ+NV3iV/KU3ebMRzqIC//DCOxzQNFNJAKldPe/bKZMCxEqtVoRkuJtNdp/5a yXFZ6TfE1hGKrDBYAm4vrnZ4CXFSBDllL59cFFOJCkn4Xboj/aVxxJxF30bn In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 10/09/2025 10.01, Mark Cave-Ayland wrote: > On 10/09/2025 06:50, Thomas Huth wrote: > >> On 12/05/2025 21.05, Paolo Bonzini wrote: >>> Now that we can do so after the error code has been pushed, raising >>> the #DB exception for task-switch traps is trivial. >>> >>> Signed-off-by: Paolo Bonzini >>> --- >>>   target/i386/tcg/seg_helper.c | 9 +++++---- >>>   1 file changed, 5 insertions(+), 4 deletions(-) >>> >>> diff --git a/target/i386/tcg/seg_helper.c b/target/i386/tcg/seg_helper.c >>> index cb90ccd2adc..071f3fbd83d 100644 >>> --- a/target/i386/tcg/seg_helper.c >>> +++ b/target/i386/tcg/seg_helper.c >>> @@ -473,10 +473,6 @@ static void switch_tss_ra(CPUX86State *env, int >>> tss_selector, >>>           new_segs[R_GS] = 0; >>>           new_trap = 0; >>>       } >>> -    /* XXX: avoid a compiler warning, see >>> -     https://urldefense.proofpoint.com/v2/url? >>> u=http-3A__support.amd.com_us_Processor-5FTechDocs_24593.pdf&d=DwICaQ&c=s883GpUCOChKOHiocYtGcg&r=c23RpsaH4D2MKyD3EPJTDa0BAxz6tV8aUJqVSoytEiY&m=ne1e2OYZDArdmBhjIXmv-d6hN8DFQV2i9elKEJJ2rgw_Rjs4bbFAj9BI-B8Y8SUa&s=Lx1uoh3Mv7iduPgFcshKa1nly0lcsCF6Z1G0neDOxQ4&e= -     chapters 12.2.5 and 13.2.4 on how to implement TSS Trap bit */ >>> -    (void)new_trap; >>>       /* clear busy bit (it is restartable) */ >>>       if (source == SWITCH_TSS_JMP || source == SWITCH_TSS_IRET) { >>> @@ -622,6 +618,11 @@ static void switch_tss_ra(CPUX86State *env, int >>> tss_selector, >>>           } >>>           SET_ESP(sa.sp, sa.sp_mask); >>>       } >>> + >>> +    if (new_trap) { >>> +        env->dr[6] |= DR6_BT; >>> +        raise_exception_ra(env, EXCP01_DB, retaddr); >>> +    } >>>   } >> >>   Hi Paolo, >> >> as already quickly mentioned in IRC, the kvm-unit-tests CI had a >> regression after homebrew updated its QEMU from 10.0 to 10.1, the >> "eventinj" and the "taskwitch" test started failing: >> >> 10.0:  https://urldefense.proofpoint.com/v2/url? >> u=https-3A__gitlab.com_kvm-2Dunit-2Dtests_kvm-2Dunit-2Dtests_-2D_jobs_10871048973&d=DwICaQ&c=s883GpUCOChKOHiocYtGcg&r=c23RpsaH4D2MKyD3EPJTDa0BAxz6tV8aUJqVSoytEiY&m=ne1e2OYZDArdmBhjIXmv-d6hN8DFQV2i9elKEJJ2rgw_Rjs4bbFAj9BI-B8Y8SUa&s=2-qwz0tlJsb4ChkM4ZqunWv6Bmf3Zri5BDO1guawTyc&e= 10.1:  https://urldefense.proofpoint.com/v2/url?u=https-3A__gitlab.com_kvm-2Dunit-2Dtests_kvm-2Dunit-2Dtests_-2D_jobs_11282832498&d=DwICaQ&c=s883GpUCOChKOHiocYtGcg&r=c23RpsaH4D2MKyD3EPJTDa0BAxz6tV8aUJqVSoytEiY&m=ne1e2OYZDArdmBhjIXmv-d6hN8DFQV2i9elKEJJ2rgw_Rjs4bbFAj9BI-B8Y8SUa&s=U7Y_mIKPuJtmnCc5eDadnSt1qVAWtKHPBqnXRrPcG1s&e= >> I've now bisected the problem (painfully in the terminal window of the >> cirrus-ci), and it seems to be this commit here that is causing the issue: >> >>   ad441b8b7913a26b18edbc076c74ca0cdbfa4ee5 is the first bad commit >>   commit ad441b8b7913a26b18edbc076c74ca0cdbfa4ee5 >>   Author: Paolo Bonzini >>   Date:   Wed Aug 14 12:33:02 2024 +0200 >> >>       target/i386: implement TSS trap bit >> >> Could you please have a look? >> >>   Thanks, >>    Thomas > > Possibly related: https://gitlab.com/qemu-project/qemu/-/issues/3101? The > submitter has also provided a suggested patch. Well spotted! I can confirm that that patch fixes the problem with the kvm-unit-tests, too! Thomas