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Tue, 08 Sep 2026 06:01:53 -0700 (PDT) Message-ID: <92b0a72a-44df-424f-acbe-58d7167f1c4d@suse.com> Date: Tue, 8 Sep 2026 15:01:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: [PATCH 2/6] x86/pass-through: no locking around pt_irq_{create,destroy}_bind() From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Teddy Astie , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Julian Vetter References: Content-Language: en-US Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-purgate-ID: tlsNG-42698a/1788872513-196C29EA-04DCD6D1/0/0 X-purgate-type: clean X-purgate-size: 1703 The questionable use of pcidevs_lock() there was discussed more than once. It really is pointless: The functions synchronize primarily via the per- domain event lock. They also may already be called with the global PCI devices lock not held: See hvm/vmsi.c:vpci_msi_update(), hvm/vmsi.c:vpci_msi_arch_update(), and hvm/vmsi.c:vpci_msi_disable(). Signed-off-by: Jan Beulich --- a/xen/arch/x86/domctl.c +++ b/xen/arch/x86/domctl.c @@ -636,10 +636,7 @@ long arch_do_domctl( ret = -EPERM; else if ( is_iommu_enabled(d) ) { - pcidevs_lock(); ret = pt_irq_create_bind(d, bind); - pcidevs_unlock(); - if ( ret < 0 ) printk(XENLOG_G_ERR "pt_irq_create_bind failed (%ld) for %pd\n", ret, d); @@ -670,10 +667,7 @@ long arch_do_domctl( ret = -EPERM; else if ( is_iommu_enabled(d) ) { - pcidevs_lock(); ret = pt_irq_destroy_bind(d, bind); - pcidevs_unlock(); - if ( ret < 0 ) printk(XENLOG_G_ERR "pt_irq_destroy_bind failed (%ld) for %pd\n", ret, d); --- a/xen/arch/x86/hvm/vioapic.c +++ b/xen/arch/x86/hvm/vioapic.c @@ -197,7 +197,6 @@ static int vioapic_hwdom_map_gsi(unsigne return ret; } - pcidevs_lock(); ret = pt_irq_create_bind(currd, &pt_irq_bind); if ( ret ) { @@ -207,7 +206,6 @@ static int vioapic_hwdom_map_gsi(unsigne unmap_domain_pirq(currd, pirq); write_unlock(&currd->event_lock); } - pcidevs_unlock(); return ret; }