vmnet: work around skb_frag_t build failure for SLE15-SP2 and openSUSE-15.2

The kernels used in (upcoming) SLE15 SP2 and openSUSE Leap 15.2 are based
on upstream version 5.3 but have a backport of the skb_frag_t conversion to
bio_vec which reached mainline in v5.4-rc1. As we cannot easily check
availability compat_skb_frag_off() (which was also added in v5.4-rc1) and
have to resort to version check, add an exception for SLE15-SP2 and
openSUSE-15.2 kernels.

vmmon-only/linux/hostif.c

@@ -47,16 +47,13 @@
 #include <asm/asm.h>
 #include <asm/io.h>
 #include <asm/page.h>
-#include <asm/tlbflush.h>
 #include <asm/uaccess.h>
-#include <asm/irq_vectors.h>
 #include <linux/capability.h>
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/hrtimer.h>
 #include <linux/signal.h>
 #include <linux/taskstats_kern.h> // For linux/sched/signal.h without version check
-#include <linux/eventfd.h>
 
 #include "vmware.h"
 #include "x86apic.h"
@@ -618,15 +615,6 @@ HostIF_FastClockUnlock(int callerID) // IN
    MutexUnlock(&fastClockMutex, callerID);
 }
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)
-static int crosspage_set_exec(pte_t *pte, unsigned long addr, void *data)
-{
-	struct page *p = data;
-
-	set_pte(pte, mk_pte(p, VM_PAGE_KERNEL_EXEC));
-	return 0;
-}
-#endif
 
 /*
  *----------------------------------------------------------------------
@@ -647,29 +635,7 @@ static int crosspage_set_exec(pte_t *pte, unsigned long addr, void *data)
 static void *
 MapCrossPage(struct page *p)  // IN:
 {
-#if COMPAT_LINUX_VERSION_CHECK_LT(5, 8, 0)
    return vmap(&p, 1, VM_MAP, VM_PAGE_KERNEL_EXEC);
-#else
-   void *addr;
-
-   addr = vmap(&p, 1, VM_MAP, VM_PAGE_KERNEL_EXEC);
-   if (!addr)
-	   return NULL;
-
-   /* Starting with 5.8, vmap() always sets the NX bit, but the cross
-    * page needs to be executable. */
-   if (apply_to_page_range(current->mm, (unsigned long)addr, PAGE_SIZE,
-			   crosspage_set_exec, p)) {
-      vunmap(addr);
-      return NULL;
-   }
-
-   preempt_disable();
-   __flush_tlb_all();
-   preempt_enable();
-
-   return addr;
-#endif
 }
 
 
@@ -1773,11 +1739,8 @@ HostIF_EstimateLockedPageLimit(const VMDriver* vm,                // IN
 #else
    lockedPages += global_page_state(NR_PAGETABLE);
 #endif
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0)
-   /* NR_SLAB_* converted to byte counters in 5.9 */
-   lockedPages += global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B);
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 13, 0)
    /* NR_SLAB_* moved from zone to node in 4.13. */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 13, 0)
    lockedPages += global_node_page_state(NR_SLAB_UNRECLAIMABLE);
 #else
    lockedPages += global_page_state(NR_SLAB_UNRECLAIMABLE);
@@ -2408,27 +2371,6 @@ HostIF_VMLockIsHeld(VMDriver *vm) // IN
 
 #if defined(CONFIG_SMP) || defined(CONFIG_X86_UP_IOAPIC) || \
     defined(CONFIG_X86_UP_APIC) || defined(CONFIG_X86_LOCAL_APIC)
-
-#if COMPAT_LINUX_VERSION_CHECK_LT(5, 8, 0)
-static long compat_copy_from_kernel_nofault(void *dst, VA src, size_t size)
-{
-   mm_segment_t old_fs;
-   long ret;
-
-   old_fs = get_fs();
-   set_fs(KERNEL_DS);
-   ret = HostIF_CopyFromUser(dst, src, size);
-   set_fs(old_fs);
-
-   return ret;
-}
-#else
-static long compat_copy_from_kernel_nofault(void *dst, VA src, size_t size)
-{
-   return copy_from_kernel_nofault(dst, (const void *)src, size);
-}
-#endif
-
 /*
  *----------------------------------------------------------------------
  *
@@ -2448,11 +2390,15 @@ static long compat_copy_from_kernel_nofault(void *dst, VA src, size_t size)
 static Bool
 isVAReadable(VA r)  // IN:
 {
+   mm_segment_t old_fs;
    uint32 dummy;
-   long ret;
+   int ret;
 
+   old_fs = get_fs();
+   set_fs(KERNEL_DS);
    r = APICR_TO_ADDR(r, APICR_VERSION);
-   ret = compat_copy_from_kernel_nofault(&dummy, r, sizeof(dummy));
+   ret = HostIF_CopyFromUser(&dummy, r, sizeof dummy);
+   set_fs(old_fs);
 
    return ret == 0;
 }
@@ -2608,12 +2554,11 @@ HostIF_SemaphoreWait(VMDriver *vm,   // IN:
                      uint64 *args)   // IN:
 {
    struct file *file;
+   mm_segment_t old_fs;
    int res;
    int waitFD = args[0];
    int timeoutms = args[2];
    uint64 value;
-   struct poll_wqueues table;
-   unsigned int mask;
 
    ASSERT(vcpuid < vm->numVCPUs);
 
@@ -2622,29 +2567,33 @@ HostIF_SemaphoreWait(VMDriver *vm,   // IN:
       return MX_WAITERROR;
    }
 
-   poll_initwait(&table);
-   current->state = TASK_INTERRUPTIBLE;
-   mask = compat_vfs_poll(file, &table.pt);
-   if (!(mask & (POLLIN | POLLERR | POLLHUP))) {
-      vm->vmhost->vcpuSemaTask[vcpuid] = current;
-      schedule_timeout(timeoutms * HZ / 1000);  // convert to Hz
-      vm->vmhost->vcpuSemaTask[vcpuid] = NULL;
+   old_fs = get_fs();
+   set_fs(KERNEL_DS);
+
+   {
+      struct poll_wqueues table;
+      unsigned int mask;
+
+      poll_initwait(&table);
+      current->state = TASK_INTERRUPTIBLE;
+      mask = compat_vfs_poll(file, &table.pt);
+      if (!(mask & (POLLIN | POLLERR | POLLHUP))) {
+         vm->vmhost->vcpuSemaTask[vcpuid] = current;
+         schedule_timeout(timeoutms * HZ / 1000);  // convert to Hz
+         vm->vmhost->vcpuSemaTask[vcpuid] = NULL;
+      }
+      current->state = TASK_RUNNING;
+      poll_freewait(&table);
    }
-   current->state = TASK_RUNNING;
-   poll_freewait(&table);
 
    /*
     * Userland only writes in multiples of sizeof(uint64). This will allow
     * the code to happily deal with a pipe or an eventfd. We only care about
     * reading no bytes (EAGAIN - non blocking fd) or sizeof(uint64).
-    *
-    * Upstream Linux changed the function parameter types/ordering in 4.14.0.
     */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 14, 0)
-   res = kernel_read(file, file->f_pos, (char *)&value, sizeof value);
-#else
-   res = kernel_read(file, &value, sizeof value, &file->f_pos);
-#endif
+
+   res = file->f_op->read(file, (char *) &value, sizeof value, &file->f_pos);
+
    if (res == sizeof value) {
       res = MX_WAITNORMAL;
    } else {
@@ -2653,6 +2602,7 @@ HostIF_SemaphoreWait(VMDriver *vm,   // IN:
       }
    }
 
+   set_fs(old_fs);
    fput(file);
 
    /*
@@ -2739,8 +2689,8 @@ HostIF_SemaphoreForceWakeup(VMDriver *vm,       // IN:
 int
 HostIF_SemaphoreSignal(uint64 *args)  // IN:
 {
-   struct eventfd_ctx *eventfd;
    struct file *file;
+   mm_segment_t old_fs;
    int res;
    int signalFD = args[1];
    uint64 value = 1;  // make an eventfd happy should it be there
@@ -2750,34 +2700,22 @@ HostIF_SemaphoreSignal(uint64 *args)  // IN:
       return MX_WAITERROR;
    }
 
-   /*
-    * If it's eventfd, use specific eventfd interface as kernel writes
-    * to eventfd may not be allowed in kernel 5.10 and later.
-    */
-   eventfd = eventfd_ctx_fileget(file);
-   if (!IS_ERR(eventfd)) {
-      eventfd_signal(eventfd, 1);
-      fput(file);
-      return MX_WAITNORMAL;
-   }
+   old_fs = get_fs();
+   set_fs(KERNEL_DS);
 
    /*
     * Always write sizeof(uint64) bytes. This works fine for eventfd and
     * pipes. The data written is formatted to make an eventfd happy should
     * it be present.
-    *
-    * Upstream Linux changed the function parameter types/ordering in 4.14.0.
     */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 14, 0)
-   res = kernel_write(file, (char *)&value, sizeof value, file->f_pos);
-#else
-   res = kernel_write(file, &value, sizeof value, &file->f_pos);
-#endif
+
+   res = file->f_op->write(file, (char *) &value, sizeof value, &file->f_pos);
 
    if (res == sizeof value) {
       res = MX_WAITNORMAL;
    }
 
+   set_fs(old_fs);
    fput(file);
 
    /*
@@ -3324,9 +3262,12 @@ static int
 HostIFFastClockThread(void *unused)  // IN:
 {
    int res;
+   mm_segment_t oldFS;
    unsigned int rate = 0;
    unsigned int prevRate = 0;
 
+   oldFS = get_fs();
+   set_fs(KERNEL_DS);
    allow_signal(SIGKILL);
 
    while ((rate = linuxState.fastClockRate) > MIN_RATE) {
@@ -3349,6 +3290,8 @@ HostIFFastClockThread(void *unused)  // IN:
    }
 
  out:
+   set_fs(oldFS);
+
    /*
     * Do not exit thread until we are told to do so.
     */

vmnet-only/userif.c

@@ -87,24 +87,6 @@ extern unsigned int  vnet_max_qlen;
 #   define skb_frag_off(frag) (frag)->page_offset
 #endif
 
-#if COMPAT_LINUX_VERSION_CHECK_LT(5, 10, 0)
-static inline
-__wsum compat_csum_and_copy_to_user(const void *src, void __user *dst, int len)
-{
-	int err;
-	__wsum ret;
-
-	ret = csum_and_copy_to_user(src, dst, len, 0, &err);
-	return err ? 0 : ret;
-}
-#else
-static inline
-__wsum compat_csum_and_copy_to_user(const void *src, void __user *dst, int len)
-{
-	return csum_and_copy_to_user(src, dst, len);
-}
-#endif
-
 /*
  *-----------------------------------------------------------------------------
  *
@@ -566,6 +548,7 @@ VNetCsumCopyDatagram(const struct sk_buff *skb,	// IN: skb to copy
 		     char *buf)			// OUT: where to copy data
 {
    unsigned int csum;
+   int err = 0;
    int len = skb_headlen(skb) - offset;
    char *curr = buf;
    const skb_frag_t *frag;
@@ -578,9 +561,10 @@ VNetCsumCopyDatagram(const struct sk_buff *skb,	// IN: skb to copy
       return -EINVAL;
    }
 
-   csum = compat_csum_and_copy_to_user(skb->data + offset, curr, len);
-   if (!csum)
-	   return -EFAULT;
+   csum = csum_and_copy_to_user(skb->data + offset, curr, len, 0, &err);
+   if (err) {
+      return err;
+   }
    curr += len;
 
    for (frag = skb_shinfo(skb)->frags;
@@ -591,12 +575,13 @@ VNetCsumCopyDatagram(const struct sk_buff *skb,	// IN: skb to copy
 	 const void *vaddr;
 
 	 vaddr = kmap(skb_frag_page(frag));
-	 tmpCsum = compat_csum_and_copy_to_user(vaddr + skb_frag_off(frag),
-						curr, skb_frag_size(frag));
+	 tmpCsum = csum_and_copy_to_user(vaddr + skb_frag_off(frag),
+					 curr, skb_frag_size(frag), 0, &err);
 	 kunmap(skb_frag_page(frag));
 
-	 if (!tmpCsum)
-		 return -EFAULT;
+	 if (err) {
+	    return err;
+	 }
 	 csum = csum_block_add(csum, tmpCsum, curr - buf);
 	 curr += skb_frag_size(frag);
       }