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Re: [Xen-devel] [RFC PATCH] xen, apic: Setup our own APIC driver and validator for APIC IDs.



On Thu, Jan 22, 2015 at 10:00:55AM +0000, David Vrabel wrote:
> On 21/01/15 21:56, Konrad Rzeszutek Wilk wrote:
> > +static struct apic xen_apic = {
> > +   .name = "Xen",
> > +   .probe = probe_xen,
> > +   /* The rest is copied from the default. */
> 
> Explicitly initialize all required members here.  memcpy'ing from the
> default makes it far too unclear which ops this apic driver actually
> provides.

RFC (boots under PV, PVHVM, PV dom0):

From 27702ef618af068736d13aeadcbcacd2a6780e82 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Fri, 9 Jan 2015 17:55:52 -0500
Subject: [PATCH] xen,apic: Setup our own APIC driver and validator for APIC
 IDs.

Via CPUID masking and the different apic-> overrides we
effectively make PV guests only but with the default APIC
driver. That is OK as an PV guest should never access any
APIC registers. However, the APIC is also used to limit the
amount of CPUs if the APIC IDs are incorrect - and since we
mask the x2APIC from the CPUID - any APIC IDs above 0xFF
are deemed incorrect by the default APIC routines.

As such add a new routine to check for APIC ID which will
be only used if the CPUID (native one) tells us the system
is using x2APIC.

This allows us to boot with more than 255 CPUs if running
as initial domain.

Reported-by: Cathy Avery <cathy.avery@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 arch/x86/xen/apic.c      | 158 +++++++++++++++++++++++++++++++++++++++++++++++
 arch/x86/xen/enlighten.c |  90 +--------------------------
 2 files changed, 159 insertions(+), 89 deletions(-)

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index 7005ced..e7c2145 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -7,6 +7,7 @@
 #include <xen/xen.h>
 #include <xen/interface/physdev.h>
 #include "xen-ops.h"
+#include "smp.h"
 
 static unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
 {
@@ -28,7 +29,164 @@ static unsigned int xen_io_apic_read(unsigned apic, 
unsigned reg)
        return 0xfd;
 }
 
+static unsigned long xen_set_apic_id(unsigned int x)
+{
+       WARN_ON(1);
+       return x;
+}
+
+static unsigned int xen_get_apic_id(unsigned long x)
+{
+       return ((x)>>24) & 0xFFu;
+}
+
+static u32 xen_apic_read(u32 reg)
+{
+       struct xen_platform_op op = {
+               .cmd = XENPF_get_cpuinfo,
+               .interface_version = XENPF_INTERFACE_VERSION,
+               .u.pcpu_info.xen_cpuid = 0,
+       };
+       int ret = 0;
+
+       /* Shouldn't need this as APIC is turned off for PV, and we only
+        * get called on the bootup processor. But just in case. */
+       if (!xen_initial_domain() || smp_processor_id())
+               return 0;
+
+       if (reg == APIC_LVR)
+               return 0x10;
+
+       if (reg != APIC_ID)
+               return 0;
+
+       ret = HYPERVISOR_dom0_op(&op);
+       if (ret)
+               return 0;
+
+       return op.u.pcpu_info.apic_id << 24;
+}
+
+static void xen_apic_write(u32 reg, u32 val)
+{
+       /* Warn to see if there's any stray references */
+       WARN_ON(1);
+}
+
+static u64 xen_apic_icr_read(void)
+{
+       return 0;
+}
+
+static void xen_apic_icr_write(u32 low, u32 id)
+{
+       /* Warn to see if there's any stray references */
+       WARN_ON(1);
+}
+
+static u32 xen_safe_apic_wait_icr_idle(void)
+{
+        return 0;
+}
+
+
+static int probe_xen(void)
+{
+       if (xen_pv_domain())
+               return 1;
+
+       return 0;
+}
+
+static int xen_madt_oem_check(char *oem_id, char *oem_table_id)
+{
+       return 1;
+}
+
+static int xen_id_always_valid(int apicid)
+{
+       return 1;
+}
+
+static int xen_id_always_registered(void)
+{
+       return 1;
+}
+
+static int xen_phys_pkg_id(int initial_apic_id, int index_msb)
+{
+       return initial_apic_id >> index_msb;
+}
+
+static void xen_noop(void)
+{
+}
+
+static void xen_silent_inquire(int apicid)
+{
+}
+
+static struct apic xen_apic = {
+       .name                           = "Xen PV",
+       .probe                          = probe_xen,
+       .acpi_madt_oem_check            = xen_madt_oem_check,
+       .apic_id_valid                  = xen_id_always_valid,
+       .apic_id_registered             = xen_id_always_registered,
+
+       .irq_delivery_mode              = 0xbeef, /* used in 
native_compose_msi_msg only */
+       .irq_dest_mode                  = 0xbeef, /* used in 
native_compose_msi_msg only */
+
+       .target_cpus                    = default_target_cpus,
+       .disable_esr                    = 0,
+       .dest_logical                   = 0, /* default_send_IPI_ use it but we 
use our own. */
+       .check_apicid_used              = default_check_apicid_used, /* Used on 
32-bit */
+
+       .vector_allocation_domain       = flat_vector_allocation_domain,
+       .init_apic_ldr                  = xen_noop, /* setup_local_APIC calls 
it */
+
+       .ioapic_phys_id_map             = default_ioapic_phys_id_map, /* Used 
on 32-bit */
+       .setup_apic_routing             = NULL,
+       .cpu_present_to_apicid          = default_cpu_present_to_apicid,
+       .apicid_to_cpu_present          = physid_set_mask_of_physid, /* Used on 
32-bit */
+       .check_phys_apicid_present      = default_check_phys_apicid_present, /* 
smp_sanity_check needs it */
+       .phys_pkg_id                    = xen_phys_pkg_id, /* detect_ht */
+
+       .get_apic_id                    = xen_get_apic_id,
+       .set_apic_id                    = xen_set_apic_id, /* Can be NULL on 
32-bit. */
+       .apic_id_mask                   = 0xFF << 24, /* Used by 
verify_local_APIC. Match with what xen_get_apic_id does. */
+
+       .cpu_mask_to_apicid_and         = flat_cpu_mask_to_apicid_and,
+
+       .send_IPI_mask                  = xen_send_IPI_mask,
+       .send_IPI_mask_allbutself       = xen_send_IPI_mask_allbutself,
+       .send_IPI_allbutself            = xen_send_IPI_allbutself,
+       .send_IPI_all                   = xen_send_IPI_all,
+       .send_IPI_self                  = xen_send_IPI_self,
+
+       .wait_for_init_deassert         = false, /* Used by AP bootup - 
smp_callin which we don't use */
+       .inquire_remote_apic            = xen_silent_inquire,
+
+       .read                           = xen_apic_read,
+       .write                          = xen_apic_write,
+       .eoi_write                      = xen_apic_write,
+
+       .icr_read                       = xen_apic_icr_read,
+       .icr_write                      = xen_apic_icr_write,
+       .wait_icr_idle                  = xen_noop,
+       .safe_wait_icr_idle             = xen_safe_apic_wait_icr_idle,
+
+#ifdef CONFIG_X86_32
+       /* generic_processor_info */
+       .x86_32_early_logical_apicid    = default_x86_32_early_logical_apicid,
+#endif
+};
+
 void __init xen_init_apic(void)
 {
        x86_io_apic_ops.read = xen_io_apic_read;
+       /* On PV guests the APIC CPUID bit is disabled so none of the
+        * routines end up executing. */
+       if (!xen_initial_domain())
+               apic = &xen_apic;
 }
+apic_driver(xen_apic);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 78a881b..6c13a45 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -927,92 +927,6 @@ static void xen_io_delay(void)
 {
 }
 
-#ifdef CONFIG_X86_LOCAL_APIC
-static unsigned long xen_set_apic_id(unsigned int x)
-{
-       WARN_ON(1);
-       return x;
-}
-static unsigned int xen_get_apic_id(unsigned long x)
-{
-       return ((x)>>24) & 0xFFu;
-}
-static u32 xen_apic_read(u32 reg)
-{
-       struct xen_platform_op op = {
-               .cmd = XENPF_get_cpuinfo,
-               .interface_version = XENPF_INTERFACE_VERSION,
-               .u.pcpu_info.xen_cpuid = 0,
-       };
-       int ret = 0;
-
-       /* Shouldn't need this as APIC is turned off for PV, and we only
-        * get called on the bootup processor. But just in case. */
-       if (!xen_initial_domain() || smp_processor_id())
-               return 0;
-
-       if (reg == APIC_LVR)
-               return 0x10;
-
-       if (reg != APIC_ID)
-               return 0;
-
-       ret = HYPERVISOR_dom0_op(&op);
-       if (ret)
-               return 0;
-
-       return op.u.pcpu_info.apic_id << 24;
-}
-
-static void xen_apic_write(u32 reg, u32 val)
-{
-       /* Warn to see if there's any stray references */
-       WARN_ON(1);
-}
-
-static u64 xen_apic_icr_read(void)
-{
-       return 0;
-}
-
-static void xen_apic_icr_write(u32 low, u32 id)
-{
-       /* Warn to see if there's any stray references */
-       WARN_ON(1);
-}
-
-static void xen_apic_wait_icr_idle(void)
-{
-        return;
-}
-
-static u32 xen_safe_apic_wait_icr_idle(void)
-{
-        return 0;
-}
-
-static void set_xen_basic_apic_ops(void)
-{
-       apic->read = xen_apic_read;
-       apic->write = xen_apic_write;
-       apic->icr_read = xen_apic_icr_read;
-       apic->icr_write = xen_apic_icr_write;
-       apic->wait_icr_idle = xen_apic_wait_icr_idle;
-       apic->safe_wait_icr_idle = xen_safe_apic_wait_icr_idle;
-       apic->set_apic_id = xen_set_apic_id;
-       apic->get_apic_id = xen_get_apic_id;
-
-#ifdef CONFIG_SMP
-       apic->send_IPI_allbutself = xen_send_IPI_allbutself;
-       apic->send_IPI_mask_allbutself = xen_send_IPI_mask_allbutself;
-       apic->send_IPI_mask = xen_send_IPI_mask;
-       apic->send_IPI_all = xen_send_IPI_all;
-       apic->send_IPI_self = xen_send_IPI_self;
-#endif
-}
-
-#endif
-
 static void xen_clts(void)
 {
        struct multicall_space mcs;
@@ -1601,7 +1515,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
        /*
         * set up the basic apic ops.
         */
-       set_xen_basic_apic_ops();
+       xen_init_apic();
 #endif
 
        if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
@@ -1714,8 +1628,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
                if (HYPERVISOR_dom0_op(&op) == 0)
                        boot_params.kbd_status = 
op.u.firmware_info.u.kbd_shift_flags;
 
-               xen_init_apic();
-
                /* Make sure ACS will be enabled */
                pci_request_acs();
 
-- 
2.1.0


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