[PATCH v6 03/11] x86/mmcfg: add handlers for the PVH Dom0 MMCFG areas

[Roger Pau Monne <roger.pau@citrix.com>]

Introduce a set of handlers for the accesses to the MMCFG areas. Those
areas are setup based on the contents of the hardware MMCFG tables,
and the list of handled MMCFG areas is stored inside of the hvm_domain
struct.

The read/writes are forwarded to the generic vpci handlers once the
address is decoded in order to obtain the device and register the
guest is trying to access.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Paul Durrant <paul.durrant@citrix.com>
---
Changes since v5:
 - Switch to use pci_sbdf_t.
 - Switch to the new per vpci locks.
 - Move the mmcfg related external definitions to asm-x86/pci.h

Changes since v4:
 - Change the attribute of pvh_setup_mmcfg to __hwdom_init.
 - Try to add as many MMCFG regions as possible, even if one fails to
   add.
 - Change some fields of the hvm_mmcfg struct: turn size into a
   unsigned int, segment into uint16_t and bus into uint8_t.
 - Convert some address parameters from unsigned long to paddr_t for
   consistency.
 - Make vpci_mmcfg_decode_addr return the decoded register in the
   return of the function.
 - Introduce a new macro to convert a MMCFG address into a BDF, and
   use it in vpci_mmcfg_decode_addr to clarify the logic.
 - In vpci_mmcfg_{read/write} unify the logic for 8B accesses and
   smaller ones.
 - Add the __hwdom_init attribute to register_vpci_mmcfg_handler.
 - Test that reg + size doesn't cross a device boundary.

Changes since v3:
 - Propagate changes from previous patches: drop xen_ prefix for vpci
   functions, pass slot and func instead of devfn and fix the error
   paths of the MMCFG handlers.
 - s/ecam/mmcfg/.
 - Move the destroy code to a separate function, so the hvm_mmcfg
   struct can be private to hvm/io.c.
 - Constify the return of vpci_mmcfg_find.
 - Use d instead of v->domain in vpci_mmcfg_accept.
 - Allow 8byte accesses to the mmcfg.

Changes since v1:
 - Added locking.
---
 xen/arch/x86/hvm/dom0_build.c    |  21 +++++
 xen/arch/x86/hvm/hvm.c           |   4 +
 xen/arch/x86/hvm/io.c            | 174 ++++++++++++++++++++++++++++++++++++++-
 xen/arch/x86/x86_64/mmconfig.h   |   4 -
 xen/include/asm-x86/hvm/domain.h |   4 +
 xen/include/asm-x86/hvm/io.h     |   7 ++
 xen/include/asm-x86/pci.h        |   6 ++
 7 files changed, 215 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 020c355faf..17d77137d6 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -22,6 +22,7 @@
 #include <xen/init.h>
 #include <xen/libelf.h>
 #include <xen/multiboot.h>
+#include <xen/pci.h>
 #include <xen/softirq.h>
 
 #include <acpi/actables.h>
@@ -1048,6 +1049,24 @@ static int __init pvh_setup_acpi(struct domain *d, paddr_t start_info)
     return 0;
 }
 
+static void __hwdom_init pvh_setup_mmcfg(struct domain *d)
+{
+    unsigned int i;
+    int rc;
+
+    for ( i = 0; i < pci_mmcfg_config_num; i++ )
+    {
+        rc = register_vpci_mmcfg_handler(d, pci_mmcfg_config[i].address,
+                                         pci_mmcfg_config[i].start_bus_number,
+                                         pci_mmcfg_config[i].end_bus_number,
+                                         pci_mmcfg_config[i].pci_segment);
+        if ( rc )
+            printk("Unable to setup MMCFG handler at %#lx for segment %u\n",
+                   pci_mmcfg_config[i].address,
+                   pci_mmcfg_config[i].pci_segment);
+    }
+}
+
 int __init dom0_construct_pvh(struct domain *d, const module_t *image,
                               unsigned long image_headroom,
                               module_t *initrd,
@@ -1090,6 +1109,8 @@ int __init dom0_construct_pvh(struct domain *d, const module_t *image,
         return rc;
     }
 
+    pvh_setup_mmcfg(d);
+
     panic("Building a PVHv2 Dom0 is not yet supported.");
     return 0;
 }
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index cc73df8dc7..b1064413fc 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -581,8 +581,10 @@ int hvm_domain_initialise(struct domain *d, unsigned long domcr_flags,
     spin_lock_init(&d->arch.hvm_domain.irq_lock);
     spin_lock_init(&d->arch.hvm_domain.uc_lock);
     spin_lock_init(&d->arch.hvm_domain.write_map.lock);
+    rwlock_init(&d->arch.hvm_domain.mmcfg_lock);
     INIT_LIST_HEAD(&d->arch.hvm_domain.write_map.list);
     INIT_LIST_HEAD(&d->arch.hvm_domain.g2m_ioport_list);
+    INIT_LIST_HEAD(&d->arch.hvm_domain.mmcfg_regions);
 
     rc = create_perdomain_mapping(d, PERDOMAIN_VIRT_START, 0, NULL, NULL);
     if ( rc )
@@ -728,6 +730,8 @@ void hvm_domain_destroy(struct domain *d)
         list_del(&ioport->list);
         xfree(ioport);
     }
+
+    destroy_vpci_mmcfg(&d->arch.hvm_domain.mmcfg_regions);
 }
 
 static int hvm_save_tsc_adjust(struct domain *d, hvm_domain_context_t *h)
diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 6f9cd1f19e..7ee20eb5d4 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -274,7 +274,7 @@ unsigned int hvm_pci_decode_addr(unsigned int cf8, unsigned int addr,
 static bool vpci_access_allowed(unsigned int reg, unsigned int len)
 {
     /* Check access size. */
-    if ( len != 1 && len != 2 && len != 4 )
+    if ( len != 1 && len != 2 && len != 4 && len != 8 )
         return false;
 
     /* Check that access is size aligned. */
@@ -372,6 +372,178 @@ void register_vpci_portio_handler(struct domain *d)
     handler->ops = &vpci_portio_ops;
 }
 
+struct hvm_mmcfg {
+    struct list_head next;
+    paddr_t addr;
+    unsigned int size;
+    uint16_t segment;
+    uint8_t start_bus;
+};
+
+/* Handlers to trap PCI MMCFG config accesses. */
+static const struct hvm_mmcfg *vpci_mmcfg_find(const struct domain *d,
+                                               paddr_t addr)
+{
+    const struct hvm_mmcfg *mmcfg;
+
+    list_for_each_entry ( mmcfg, &d->arch.hvm_domain.mmcfg_regions, next )
+        if ( addr >= mmcfg->addr && addr < mmcfg->addr + mmcfg->size )
+            return mmcfg;
+
+    return NULL;
+}
+
+static unsigned int vpci_mmcfg_decode_addr(const struct hvm_mmcfg *mmcfg,
+                                           paddr_t addr, pci_sbdf_t *sbdf)
+{
+    addr -= mmcfg->addr;
+    sbdf->bdf = MMCFG_BDF(addr);
+    sbdf->bus += mmcfg->start_bus;
+    sbdf->seg = mmcfg->segment;
+
+    return addr & (PCI_CFG_SPACE_EXP_SIZE - 1);
+}
+
+static int vpci_mmcfg_accept(struct vcpu *v, unsigned long addr)
+{
+    struct domain *d = v->domain;
+    bool found;
+
+    read_lock(&d->arch.hvm_domain.mmcfg_lock);
+    found = vpci_mmcfg_find(d, addr);
+    read_unlock(&d->arch.hvm_domain.mmcfg_lock);
+
+    return found;
+}
+
+static int vpci_mmcfg_read(struct vcpu *v, unsigned long addr,
+                           unsigned int len, unsigned long *data)
+{
+    struct domain *d = v->domain;
+    const struct hvm_mmcfg *mmcfg;
+    unsigned int reg;
+    pci_sbdf_t sbdf;
+
+    *data = ~0ul;
+
+    read_lock(&d->arch.hvm_domain.mmcfg_lock);
+    mmcfg = vpci_mmcfg_find(d, addr);
+    if ( !mmcfg )
+    {
+        read_unlock(&d->arch.hvm_domain.mmcfg_lock);
+        return X86EMUL_OKAY;
+    }
+
+    reg = vpci_mmcfg_decode_addr(mmcfg, addr, &sbdf);
+    read_unlock(&d->arch.hvm_domain.mmcfg_lock);
+
+    if ( !vpci_access_allowed(reg, len) ||
+         (reg + len) > PCI_CFG_SPACE_EXP_SIZE )
+        return X86EMUL_OKAY;
+
+    /*
+     * According to the PCIe 3.1A specification:
+     *  - Configuration Reads and Writes must usually be DWORD or smaller
+     *    in size.
+     *  - Because Root Complex implementations are not required to support
+     *    accesses to a RCRB that cross DW boundaries [...] software
+     *    should take care not to cause the generation of such accesses
+     *    when accessing a RCRB unless the Root Complex will support the
+     *    access.
+     *  Xen however supports 8byte accesses by splitting them into two
+     *  4byte accesses.
+     */
+    *data = vpci_read(sbdf, reg, min(4u, len));
+    if ( len == 8 )
+        *data |= (uint64_t)vpci_read(sbdf, reg + 4, 4) << 32;
+
+    return X86EMUL_OKAY;
+}
+
+static int vpci_mmcfg_write(struct vcpu *v, unsigned long addr,
+                            unsigned int len, unsigned long data)
+{
+    struct domain *d = v->domain;
+    const struct hvm_mmcfg *mmcfg;
+    unsigned int reg;
+    pci_sbdf_t sbdf;
+
+    read_lock(&d->arch.hvm_domain.mmcfg_lock);
+    mmcfg = vpci_mmcfg_find(d, addr);
+    if ( !mmcfg )
+    {
+        read_unlock(&d->arch.hvm_domain.mmcfg_lock);
+        return X86EMUL_OKAY;
+    }
+
+    reg = vpci_mmcfg_decode_addr(mmcfg, addr, &sbdf);
+    read_unlock(&d->arch.hvm_domain.mmcfg_lock);
+
+    if ( !vpci_access_allowed(reg, len) ||
+         (reg + len) > PCI_CFG_SPACE_EXP_SIZE )
+        return X86EMUL_OKAY;
+
+    vpci_write(sbdf, reg, min(4u, len), data);
+    if ( len == 8 )
+        vpci_write(sbdf, reg + 4, 4, data >> 32);
+
+    return X86EMUL_OKAY;
+}
+
+static const struct hvm_mmio_ops vpci_mmcfg_ops = {
+    .check = vpci_mmcfg_accept,
+    .read = vpci_mmcfg_read,
+    .write = vpci_mmcfg_write,
+};
+
+int __hwdom_init register_vpci_mmcfg_handler(struct domain *d, paddr_t addr,
+                                             unsigned int start_bus,
+                                             unsigned int end_bus,
+                                             unsigned int seg)
+{
+    struct hvm_mmcfg *mmcfg;
+
+    ASSERT(is_hardware_domain(d));
+
+    write_lock(&d->arch.hvm_domain.mmcfg_lock);
+    if ( vpci_mmcfg_find(d, addr) )
+    {
+        write_unlock(&d->arch.hvm_domain.mmcfg_lock);
+        return -EEXIST;
+    }
+
+    mmcfg = xmalloc(struct hvm_mmcfg);
+    if ( !mmcfg )
+    {
+        write_unlock(&d->arch.hvm_domain.mmcfg_lock);
+        return -ENOMEM;
+    }
+
+    if ( list_empty(&d->arch.hvm_domain.mmcfg_regions) )
+        register_mmio_handler(d, &vpci_mmcfg_ops);
+
+    mmcfg->addr = addr + (start_bus << 20);
+    mmcfg->start_bus = start_bus;
+    mmcfg->segment = seg;
+    mmcfg->size = (end_bus - start_bus + 1) << 20;
+    list_add(&mmcfg->next, &d->arch.hvm_domain.mmcfg_regions);
+    write_unlock(&d->arch.hvm_domain.mmcfg_lock);
+
+    return 0;
+}
+
+void destroy_vpci_mmcfg(struct list_head *domain_mmcfg)
+{
+    while ( !list_empty(domain_mmcfg) )
+    {
+        struct hvm_mmcfg *mmcfg = list_first_entry(domain_mmcfg,
+                                                   struct hvm_mmcfg, next);
+
+        list_del(&mmcfg->next);
+        xfree(mmcfg);
+    }
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/x86/x86_64/mmconfig.h b/xen/arch/x86/x86_64/mmconfig.h
index 7537519414..2e836848ad 100644
--- a/xen/arch/x86/x86_64/mmconfig.h
+++ b/xen/arch/x86/x86_64/mmconfig.h
@@ -74,10 +74,6 @@ static inline void mmio_config_writel(void __iomem *pos, u32 val)
     asm volatile("movl %%eax,(%1)" :: "a" (val), "r" (pos) : "memory");
 }
 
-/* external variable defines */
-extern int pci_mmcfg_config_num;
-extern struct acpi_mcfg_allocation *pci_mmcfg_config;
-
 /* function prototypes */
 int acpi_parse_mcfg(struct acpi_table_header *header);
 int pci_mmcfg_reserved(uint64_t address, unsigned int segment,
diff --git a/xen/include/asm-x86/hvm/domain.h b/xen/include/asm-x86/hvm/domain.h
index d2899c9bb2..cd19ee11e9 100644
--- a/xen/include/asm-x86/hvm/domain.h
+++ b/xen/include/asm-x86/hvm/domain.h
@@ -184,6 +184,10 @@ struct hvm_domain {
     /* List of guest to machine IO ports mapping. */
     struct list_head g2m_ioport_list;
 
+    /* List of MMCFG regions trapped by Xen. */
+    struct list_head mmcfg_regions;
+    rwlock_t mmcfg_lock;
+
     /* List of permanently write-mapped pages. */
     struct {
         spinlock_t lock;
diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index f68aed9323..ba66e22e04 100644
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -163,6 +163,13 @@ void register_g2m_portio_handler(struct domain *d);
 /* HVM port IO handler for vPCI accesses. */
 void register_vpci_portio_handler(struct domain *d);
 
+/* HVM MMIO handler for PCI MMCFG accesses. */
+int register_vpci_mmcfg_handler(struct domain *d, paddr_t addr,
+                                unsigned int start_bus, unsigned int end_bus,
+                                unsigned int seg);
+/* Destroy tracked MMCFG areas. */
+void destroy_vpci_mmcfg(struct list_head *domain_mmcfg);
+
 #endif /* __ASM_X86_HVM_IO_H__ */
 
 
diff --git a/xen/include/asm-x86/pci.h b/xen/include/asm-x86/pci.h
index 36801d317b..cc05045e9c 100644
--- a/xen/include/asm-x86/pci.h
+++ b/xen/include/asm-x86/pci.h
@@ -6,6 +6,8 @@
 #define CF8_ADDR_HI(cf8) (  ((cf8) & 0x0f000000) >> 16)
 #define CF8_ENABLED(cf8) (!!((cf8) & 0x80000000))
 
+#define MMCFG_BDF(addr)  ( ((addr) & 0x0ffff000) >> 12)
+
 #define IS_SNB_GFX(id) (id == 0x01068086 || id == 0x01168086 \
                         || id == 0x01268086 || id == 0x01028086 \
                         || id == 0x01128086 || id == 0x01228086 \
@@ -26,4 +28,8 @@ bool_t pci_mmcfg_decode(unsigned long mfn, unsigned int *seg,
 bool_t pci_ro_mmcfg_decode(unsigned long mfn, unsigned int *seg,
                            unsigned int *bdf);
 
+/* MMCFG external variable defines */
+extern int pci_mmcfg_config_num;
+extern struct acpi_mcfg_allocation *pci_mmcfg_config;
+
 #endif /* __X86_PCI_H__ */
-- 
2.11.0 (Apple Git-81)


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