Provide APIs to directly get 'lowmem' and 'highmem' size directly.

Previously the sizes were inferred indirectly based on the size of the mappings
at 0 and 4GB respectively. This works fine as long as size of the allocation is
identical to the size of the mapping in the guest's address space. However, if
the mapping is disjoint then this assumption falls apart (e.g., due to the
legacy BIOS hole between 640KB and 1MB).

6 files changed, 26 insertions, 21 deletions

diff --git a/lib/libvmmapi/vmmapi.c b/lib/libvmmapi/vmmapi.c
index 5ce3d8e..9fb2308 100644
--- a/lib/libvmmapi/vmmapi.c
+++ b/lib/libvmmapi/vmmapi.c
@@ -274,6 +274,20 @@ vm_map_gpa(struct vmctx *ctx, vm_paddr_t gaddr, size_t len)
 	return (NULL);
 }
 
+size_t
+vm_get_lowmem_size(struct vmctx *ctx)
+{
+
+	return (ctx->lowmem);
+}
+
+size_t
+vm_get_highmem_size(struct vmctx *ctx)
+{
+
+	return (ctx->highmem);
+}
+
 int
 vm_set_desc(struct vmctx *ctx, int vcpu, int reg,
 	    uint64_t base, uint32_t limit, uint32_t access)
diff --git a/lib/libvmmapi/vmmapi.h b/lib/libvmmapi/vmmapi.h
index 4cc4290..067eaa0 100644
--- a/lib/libvmmapi/vmmapi.h
+++ b/lib/libvmmapi/vmmapi.h
@@ -60,6 +60,8 @@ int	vm_get_gpa_pmap(struct vmctx *, uint64_t gpa, uint64_t *pte, int *num);
 uint32_t vm_get_lowmem_limit(struct vmctx *ctx);
 void	vm_set_lowmem_limit(struct vmctx *ctx, uint32_t limit);
 void	vm_set_memflags(struct vmctx *ctx, int flags);
+size_t	vm_get_lowmem_size(struct vmctx *ctx);
+size_t	vm_get_highmem_size(struct vmctx *ctx);
 int	vm_set_desc(struct vmctx *ctx, int vcpu, int reg,
 		    uint64_t base, uint32_t limit, uint32_t access);
 int	vm_get_desc(struct vmctx *ctx, int vcpu, int reg,
diff --git a/usr.sbin/bhyve/pci_emul.c b/usr.sbin/bhyve/pci_emul.c
index a2c47ec..458ba76 100644
--- a/usr.sbin/bhyve/pci_emul.c
+++ b/usr.sbin/bhyve/pci_emul.c
@@ -1118,8 +1118,7 @@ init_pci(struct vmctx *ctx)
 	 * Accesses to memory addresses that are not allocated to system
 	 * memory or PCI devices return 0xff's.
 	 */
-	error = vm_get_memory_seg(ctx, 0, &lowmem, NULL);
-	assert(error == 0);
+	lowmem = vm_get_lowmem_size(ctx);
 
 	memset(&pci_mem_hole, 0, sizeof(struct mem_range));
 	pci_mem_hole.name = "PCI hole";
diff --git a/usr.sbin/bhyve/rtc.c b/usr.sbin/bhyve/rtc.c
index 1187747..b3631fc 100644
--- a/usr.sbin/bhyve/rtc.c
+++ b/usr.sbin/bhyve/rtc.c
@@ -343,19 +343,14 @@ rtc_init(struct vmctx *ctx)
 	 * 0x34/0x35 - 64KB chunks above 16MB, below 4GB
 	 * 0x5b/0x5c/0x5d - 64KB chunks above 4GB
 	 */
-	err = vm_get_memory_seg(ctx, 0, &lomem, NULL);
-	assert(err == 0);
-
-	lomem = (lomem - m_16MB) / m_64KB;
+	lomem = (vm_get_lowmem_size(ctx) - m_16MB) / m_64KB;
 	rtc_nvram[nvoff(RTC_LMEM_LSB)] = lomem;
 	rtc_nvram[nvoff(RTC_LMEM_MSB)] = lomem >> 8;
 
-	if (vm_get_memory_seg(ctx, m_4GB, &himem, NULL) == 0) {	  
-		himem /= m_64KB;
-		rtc_nvram[nvoff(RTC_HMEM_LSB)] = himem;
-		rtc_nvram[nvoff(RTC_HMEM_SB)]  = himem >> 8;
-		rtc_nvram[nvoff(RTC_HMEM_MSB)] = himem >> 16;
-	}
+	himem = vm_get_highmem_size(ctx) / m_64KB;
+	rtc_nvram[nvoff(RTC_HMEM_LSB)] = himem;
+	rtc_nvram[nvoff(RTC_HMEM_SB)]  = himem >> 8;
+	rtc_nvram[nvoff(RTC_HMEM_MSB)] = himem >> 16;
 }
 
 INOUT_PORT(rtc, IO_RTC, IOPORT_F_INOUT, rtc_addr_handler);
diff --git a/usr.sbin/bhyve/smbiostbl.c b/usr.sbin/bhyve/smbiostbl.c
index 9d1cfb3..d560f02 100644
--- a/usr.sbin/bhyve/smbiostbl.c
+++ b/usr.sbin/bhyve/smbiostbl.c
@@ -779,13 +779,8 @@ smbios_build(struct vmctx *ctx)
 	int				i;
 	int				err;
 
-	err = vm_get_memory_seg(ctx, 0, &guest_lomem, NULL);
-	if (err != 0)
-		return (err);
-
-	err = vm_get_memory_seg(ctx, 4*GB, &guest_himem, NULL);
-	if (err != 0)
-		return (err);
+	guest_lomem = vm_get_lowmem_size(ctx);
+	guest_himem = vm_get_highmem_size(ctx);
 
 	startaddr = paddr_guest2host(ctx, SMBIOS_BASE, SMBIOS_MAX_LENGTH);
 	if (startaddr == NULL) {
diff --git a/usr.sbin/bhyveload/bhyveload.c b/usr.sbin/bhyveload/bhyveload.c
index 4442496..ff6b269 100644
--- a/usr.sbin/bhyveload/bhyveload.c
+++ b/usr.sbin/bhyveload/bhyveload.c
@@ -505,8 +505,8 @@ static void
 cb_getmem(void *arg, uint64_t *ret_lowmem, uint64_t *ret_highmem)
 {
 
-	vm_get_memory_seg(ctx, 0, ret_lowmem, NULL);
-	vm_get_memory_seg(ctx, 4 * GB, ret_highmem, NULL);
+	*ret_lowmem = vm_get_lowmem_size(ctx);
+	*ret_highmem = vm_get_highmem_size(ctx);
 }
 
 struct env {