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[82.70.146.41]) by smtp.googlemail.com with ESMTPSA id b5-20020adfd1c5000000b0020a7954a974sm12215010wrd.34.2022.04.19.08.03.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Apr 2022 08:03:26 -0700 (PDT) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list X-Inumbo-ID: dddc03be-bff1-11ec-8fbf-03012f2f19d4 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=5ClOMvzXUkEMDZ0b8UX4E1pNgQWl3nMR7i1rQInvtkA=; b=l4Vm7kfYuqYnkN+yNN1YEBG+gVk2Z2v5+UD+QlI2xxQYbg04DbKA8rG/wA3Zf1V7Dl HP0At6uk4b3bKNgA0k2yZHrxUMSKWi+Ms8Wh9e+C6Dq6N1kB0ZNgAX/AVvyrpaXPfoHD WAlwHZhJb1wKy4b3WZjSob2GNfYvey6V014O/pWjFB82aue+oTVQC4xE7zPmrn03I0HB XmC+VrrCAHCWi2RvOWDaacq37aiW0se6nh5HXpt0+uTtyodg2GAB+O7D6RMAqfHe2QfP hfC2J7CHnTItmHk6wsx0pbWEySVDB2Gp+QD4QVloYsR3W6EXiJv2xtc0JS8NDDULR2bZ Wfcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=5ClOMvzXUkEMDZ0b8UX4E1pNgQWl3nMR7i1rQInvtkA=; b=Y86LvhmuSnT4kV4sqMso8HuLcYl6m87x+9eqQlVbeBQYzDpgCzMqHjK6Rodm9LtOH+ uMbIQCj1JZItfvDWOBgIgGUOW2tRJ/x7JrDp5CvcZj3mBMTcTp50XBlSWbE0E5BXtWZm PuZKHIRQzLCPv3Igu6FuFEesEDlfPNwx+MECSOgGdnXHDwv9aByN0QF3eQc7fe3iqadW OFlkKt67UTazUkeWRgNJ05+fGc5DcU54fbCmAZ/UUikd9xcXDIIGU+4mIKEy3uZSYD7e ru+hieaqzuE/oU2SHioGvglmmK46VOtjKi/d5opNoMDi3jnv9CU7Jmm83bQDNsCHF1if u61g== X-Gm-Message-State: AOAM530kGmo88Jcm9Cm8uWc7Gsz0+pF0KuP/v5DHXvhxKtNKvnEtrl/7 1z+fjOCRaozrdzYGP/mQsoQhoTq3iotouw== X-Google-Smtp-Source: ABdhPJxKiy/MO4DHrk2AtR3HqnzpF0BXjLoj/y89IrNGazTUrbnRVgCpjbztsfjfDcxs9EzcDpVbVA== X-Received: by 2002:adf:ba8f:0:b0:1e9:4afb:179b with SMTP id p15-20020adfba8f000000b001e94afb179bmr12257122wrg.57.1650380606754; Tue, 19 Apr 2022 08:03:26 -0700 (PDT) Sender: David Vrabel From: David Vrabel To: xen-devel@lists.xenproject.org Cc: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu , David Vrabel Subject: [PATCH v1] x86/mm: avoid inadvertently degrading a TLB flush to local only Date: Tue, 19 Apr 2022 16:03:20 +0100 Message-Id: <20220419150320.64783-1-dvrabel@cantab.net> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1650380644659100001 Content-Type: text/plain; charset="utf-8" From: David Vrabel If the direct map is incorrectly modified with interrupts disabled, the required TLB flushes are degraded to flushing the local CPU only. This could lead to very hard to diagnose problems as different CPUs will end up with different views of memory. Although, no such issues have yet been identified. Change the check in the flush_area() macro to look at system_state instead. This defers the switch from local to all later in the boot (see xen/arch/x86/setup.c:__start_xen()). This is fine because additional PCPUs are not brought up until after the system state is SYS_STATE_smp_boot. Signed-off-by: David Vrabel Reviewed-by: Jan Beulich --- xen/arch/x86/mm.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index c271e383b5..72dbce43b1 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -5071,11 +5071,10 @@ l1_pgentry_t *virt_to_xen_l1e(unsigned long v) #define lNf_to_l1f(f) (((f) & _PAGE_PRESENT) ? ((f) & ~_PAGE_PSE) : (f)) =20 /* - * map_pages_to_xen() can be called with interrupts disabled during - * early bootstrap. In this case it is safe to use flush_area_local() - * and avoid locking because only the local CPU is online. + * map_pages_to_xen() can be called early in boot before any other + * CPUs are online. Use flush_area_local() in this case. */ -#define flush_area(v,f) (!local_irq_is_enabled() ? \ +#define flush_area(v,f) (system_state < SYS_STATE_smp_boot ? \ flush_area_local((const void *)v, f) : \ flush_area_all((const void *)v, f)) =20 --=20 2.30.2