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VCPI: alias map high VCPI pages for EMS
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Some VCPI applications rely on page table mappings between the EMS page
frame and high memory, so we must set them up and release them on demand
as alias mappings.
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@bartoldeman
bartoldeman committed Feb 21, 2023
1 parent 290e76f commit 811f43b
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Showing 2 changed files with 94 additions and 17 deletions.
2 changes: 1 addition & 1 deletion src/arch/linux/mapping/mapping.c
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Original file line number Diff line number Diff line change
Expand Up @@ -487,7 +487,7 @@ int restore_mapping(int cap, dosaddr_t targ, size_t mapsize)
{
void *addr;
void *target;
assert((cap & MAPPING_DPMI) && (targ != (dosaddr_t)-1));
assert((cap & (MAPPING_DPMI|MAPPING_EMS)) && (targ != (dosaddr_t)-1));
target = MEM_BASE32(targ);
addr = mmap_mapping(cap, target, mapsize, PROT_READ | PROT_WRITE);
return (addr == target ? 0 : -1);
Expand Down
109 changes: 93 additions & 16 deletions src/dosext/misc/emm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -218,6 +218,8 @@ static struct handle_record {
u_short saved_mappings_handle[EMM_MAX_SAVED_PHYS];
u_short saved_mappings_logical[EMM_MAX_SAVED_PHYS];
int saved_mapping;
int *vcpi_high_aliases;
int nvcpi_high_aliases;
} handle_info[MAX_HANDLES];

#define OS_HANDLE 0
Expand All @@ -231,6 +233,7 @@ static u_short os_allow=1;
static inline int unmap_page(int);
static int get_map_registers(struct emm_reg *buf, int pages);
static void set_map_registers(const struct emm_reg *buf, int pages);
static void vcpi_release_high_aliases(struct handle_record *hi);

/* FIXME -- inline function */
#define CHECK_OS_HANDLE(handle) \
Expand Down Expand Up @@ -443,7 +446,8 @@ static int emm_deallocate_handle(int handle)
handle_info[handle].numpages = 0;
handle_info[handle].active = 0;
handle_info[handle].object = NULL;
CLEAR_HANDLE_NAME(handle_info[i].name);
vcpi_release_high_aliases(&handle_info[handle]);
CLEAR_HANDLE_NAME(handle_info[handle].name);
handle_total--;
emm_allocated -= numpages;
return (TRUE);
Expand Down Expand Up @@ -920,6 +924,8 @@ reallocate_pages(struct vm86_regs * state)
else {
handle_info[handle].object = obj;
handle_info[handle].numpages = newcount;
if (diff < 0)
vcpi_release_high_aliases(&handle_info[handle]);
SETHI_BYTE(state->eax, EMM_NO_ERR);
}
}
Expand All @@ -934,6 +940,7 @@ reallocate_pages(struct vm86_regs * state)
destroy_memory_object(handle_info[handle].object,handle_info[handle].numpages*EMM_PAGE_SIZE);
handle_info[handle].object = 0;
handle_info[handle].numpages = 0;
vcpi_release_high_aliases(&handle_info[handle]);
SETHI_BYTE(state->eax, EMM_NO_ERR);
}
else {
Expand Down Expand Up @@ -1870,6 +1877,66 @@ static int vcpi_allocated_total(void)
return emm_allocated * EMM_PAGE_PAGES + vcpi_allocated;
}

/* given a physical low EMS page (e.g 0=0xe000-0xe3ff), find
the logical EMS page and its corresponding memory.
Then allocate 4 pages (1 EMS page) in VCPI memory, and
alias map that area to the same place as the low EMS
page. Some VCPI applications use int67/de06 and the
resulting high page must be aliased and correspond to
a page table entry. Called by int67/de01 and de06.
Returns the DOS address of the new high alias map.
*/
static dosaddr_t vcpi_get_high_alias(int physical_page)
{
int i, logical_page, vcpi_page;
struct handle_record *hi;

int handle = emm_map[physical_page].handle;
if (handle == NULL_HANDLE || handle == OS_HANDLE)
return 0;

hi = &handle_info[handle];
hi->vcpi_high_aliases = realloc(hi->vcpi_high_aliases,
hi->numpages * sizeof(*hi->vcpi_high_aliases));
for (i = hi->nvcpi_high_aliases; i < hi->numpages; i++)
hi->vcpi_high_aliases[i] = -1;
hi->nvcpi_high_aliases = hi->numpages;

logical_page = emm_map[physical_page].logical_page;
vcpi_page = hi->vcpi_high_aliases[logical_page];
if (vcpi_page == -1) {
vcpi_page = pgaalloc(vcpi_pgapool, EMM_PAGE_PAGES, 0);
hi->vcpi_high_aliases[logical_page] = vcpi_page;
alias_mapping(MAPPING_EMS, VCPI_BASE + (vcpi_page << PAGE_SHIFT),
EMM_PAGE_SIZE, PROT_READ|PROT_WRITE|PROT_EXEC,
hi->object + logical_page*EMM_PAGE_SIZE);
}
return VCPI_BASE + (vcpi_page << PAGE_SHIFT);
}

/* Restores (unaliases) the high memory mapped above for a
given handle. Called from regular EMS handle functions.
Either this unaliases everything, or starting at a non-zero
number for a shrinking remap. */
static void vcpi_release_high_aliases(struct handle_record *hi)
{
int i;
if (!config.vcpi || !hi->vcpi_high_aliases) return;

for (i = hi->numpages; i < hi->nvcpi_high_aliases; i++)
if (hi->vcpi_high_aliases[i] != -1) {
restore_mapping(MAPPING_EMS,
VCPI_BASE + (hi->vcpi_high_aliases[i] << PAGE_SHIFT),
EMM_PAGE_SIZE);
pgafree(vcpi_pgapool, hi->vcpi_high_aliases[i]);
}
hi->nvcpi_high_aliases = hi->numpages;
if (hi->nvcpi_high_aliases == 0) {
free(hi->vcpi_high_aliases);
hi->vcpi_high_aliases = NULL;
}
}

static void vcpi_interface(struct vm86_regs *state)
{
E_printf("VCPI: al=0x%02x\n", LO_BYTE(state->eax));
Expand All @@ -1888,6 +1955,15 @@ static void vcpi_interface(struct vm86_regs *state)
SETHI_BYTE(state->eax, 0x00);
state->ebx = kvm_vcpi_get_pmi(pagetable, gdt, &pages);
SETLO_WORD(state->edi, LO_WORD(state->edi) + pages*4);
/* adjust page table so EMS mappings point to VCPI memory */
for (int phys = 0; phys < config.ems_uma_pages; phys++) {
dosaddr_t target = vcpi_get_high_alias(phys);
if (target) {
int lowpage = PHYS_PAGE_ADDR(phys) >> PAGE_SHIFT;
int prot = read_dword(pagetable + lowpage * 4) & (PAGE_SIZE - 1);
write_dword(pagetable + lowpage * 4, target | prot);
}
}
}
break;
case 0x02: /* get maximum physical memory address */
Expand All @@ -1901,17 +1977,11 @@ static void vcpi_interface(struct vm86_regs *state)
case 0x04: /* allocate a 4k page */
state->edx = 0xffffffff;
SETHI_BYTE(state->eax, EMM_OUT_OF_LOG);
if (vcpi_allocated_total() >= VCPI_TOTAL) break;
if (vcpi_pgapool == NULL) {
if (vcpi_allocated_total() < VCPI_TOTAL) {
/* we don't need to actually alias map into allocated EMS.
memory, as we can just use physical RAM, and past
XMS is available (at 16MB unless $_xms=(0)). */
assert(VCPI_BASE < 16*1024*1024);
vcpi_pgapool = pgainit(VCPI_TOTAL - vcpi_allocated_total());
E_printf("VCPI: allocated pool at 0x%08x\n", VCPI_BASE);
}
if (vcpi_pgapool)
{
assert(VCPI_BASE <= 16*1024*1024);
int page = pgaalloc(vcpi_pgapool, 1, 0);
if (page < 0) break;
vcpi_allocated++;
Expand All @@ -1922,25 +1992,29 @@ static void vcpi_interface(struct vm86_regs *state)
break;
case 0x05: /* free a 4k page */
SETHI_BYTE(state->eax, EMM_LOG_OUT_RAN);
if (VCPI_BASE && vcpi_pgapool && vcpi_allocated &&
if (VCPI_BASE && vcpi_allocated &&
state->edx >= VCPI_BASE &&
state->edx < VCPI_BASE + (VCPI_TOTAL << PAGE_SHIFT)) {
dosaddr_t addr = state->edx & PAGE_MASK;
pgafree(vcpi_pgapool, (addr - VCPI_BASE) >> PAGE_SHIFT);
vcpi_allocated--;
E_printf("VCPI: freed page at 0x%08x\n", addr);
if (vcpi_allocated == 0) {
E_printf("VCPI: freed pool at 0x%08x\n", VCPI_BASE);
pgadone(vcpi_pgapool);
vcpi_pgapool = 0;
}
SETHI_BYTE(state->eax, 0);
}
break;
case 0x06: /* get physical address of 4k page in 1st MB */
if (LO_WORD(state->ecx) < 1024*1024/PAGE_SIZE) {
int seg = FP_SEG32(LO_WORD(state->ecx) << PAGE_SHIFT);
int phys = SEG_TO_PHYS(seg);
SETHI_BYTE(state->eax, 0x00);
state->edx = LO_WORD(state->ecx) << PAGE_SHIFT;
state->edx = SEGOFF2LINEAR(seg, 0);
if (phys != -1) {
dosaddr_t target = vcpi_get_high_alias(phys);
if (target)
state->edx = target + (state->edx - PHYS_PAGE_ADDR(phys));
}
E_printf("VCPI: low page=0x%02x physical address=0x%08x\n",
LO_WORD(state->ecx), state->edx);
}
else {
SETHI_BYTE(state->eax, EMM_ILL_PHYS);
Expand Down Expand Up @@ -2449,6 +2523,9 @@ void ems_init(void)
emm_map[i + cnv_pages_start].phys_seg = cnv_start_seg + 0x400 * i;
E_printf("EMS: initialized %i pages\n", phys_pages);

if (config.vcpi)
vcpi_pgapool = pgainit((config.ems_size * 1024) >> PAGE_SHIFT);

ems_reset2();

hlt_hdlr.name = "EMS APMAP ret";
Expand Down

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