68 lines
3.1 KiB
Diff
68 lines
3.1 KiB
Diff
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From feec0d41c0737ce46860fd7b34324d41498fdb9d Mon Sep 17 00:00:00 2001
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From: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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Date: Fri, 24 Nov 2023 08:20:17 +0000
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Subject: [PATCH] xen/pass-through: merge emulated bits correctly mainline
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inclusion commit be9c61da9fc57eb7d293f380d0805ca6f46c2657 category: bugfix
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---------------------------------------------------------------
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In xen_pt_config_reg_init(), there is an error in the merging of the
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emulated data with the host value. With the current Qemu, instead of
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merging the emulated bits with the host bits as defined by emu_mask,
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the emulated bits are merged with the host bits as defined by the
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inverse of emu_mask. In some cases, depending on the data in the
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registers on the host, the way the registers are setup, and the
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initial values of the emulated bits, the end result will be that
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the register is initialized with the wrong value.
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To correct this error, use the XEN_PT_MERGE_VALUE macro to help ensure
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the merge is done correctly.
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This correction is needed to resolve Qemu project issue #1061, which
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describes the failure of Xen HVM Linux guests to boot in certain
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configurations with passed through PCI devices, that is, when this error
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disables instead of enables the PCI_STATUS_CAP_LIST bit of the
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PCI_STATUS register of a passed through PCI device, which in turn
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disables the MSI-X capability of the device in Linux guests with the end
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result being that the Linux guest never completes the boot process.
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Fixes: 2e87512eccf3 ("xen/pt: Sync up the dev.config and data values")
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1061
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Buglink: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=988333
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Signed-off-by: Chuck Zmudzinski <brchuckz@aol.com>
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Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
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Message-Id: <e4392535d8e5266063dc5461d0f1d301e3dd5951.1656522217.git.brchuckz@aol.com>
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Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
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Signed-off-by: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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---
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hw/xen/xen_pt_config_init.c | 11 ++++++-----
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1 file changed, 6 insertions(+), 5 deletions(-)
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diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
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index e7bcbe4c4f..d04c12ce3d 100644
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--- a/hw/xen/xen_pt_config_init.c
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+++ b/hw/xen/xen_pt_config_init.c
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@@ -1965,11 +1965,12 @@ static void xen_pt_config_reg_init(XenPCIPassthroughState *s,
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if ((data & host_mask) != (val & host_mask)) {
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uint32_t new_val;
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-
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- /* Mask out host (including past size). */
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- new_val = val & host_mask;
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- /* Merge emulated ones (excluding the non-emulated ones). */
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- new_val |= data & host_mask;
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+ /*
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+ * Merge the emulated bits (data) with the host bits (val)
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+ * and mask out the bits past size to enable restoration
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+ * of the proper value for logging below.
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+ */
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+ new_val = XEN_PT_MERGE_VALUE(val, data, host_mask) & size_mask;
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/* Leave intact host and emulated values past the size - even though
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* we do not care as we write per reg->size granularity, but for the
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* logging below lets have the proper value. */
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--
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2.27.0
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