Files
Atmosphere/thermosphere/src/hvisor_guest_memory.cpp
2021-02-19 21:52:35 +00:00

241 lines
9.3 KiB
C++

/*
* Copyright (c) 2019-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "hvisor_virtual_gic.hpp"
#include "hvisor_safe_io_copy.hpp"
#include "cpu/hvisor_cpu_caches.hpp"
#include "cpu/hvisor_cpu_interrupt_mask_guard.hpp"
using namespace ams::hvisor;
using namespace ams::hvisor::cpu;
namespace {
template<typename T>
T ReadBufferValue(const void *buf, size_t off)
{
static_assert(std::is_unsigned_v<T> && sizeof(T) <= 4);
T ret;
std::memcpy(&ret, reinterpret_cast<const u8 *>(buf) + off, sizeof(T));
return ret;
}
template<typename T>
void WriteBufferValue(void *buf, size_t off, T val)
{
static_assert(std::is_unsigned_v<T> && sizeof(T) <= 4);
std::memcpy(reinterpret_cast<u8 *>(buf) + off, T, sizeof(T));
}
size_t GuestReadWriteGicd(size_t offset, size_t size, void *readBuf, const void *writeBuf)
{
auto &vgic = VirtualGic::GetInstance();
if (readBuf != nullptr) {
size_t readOffset = 0;
size_t rem = size;
while (rem > 0) {
if ((offset + readOffset) % 4 == 0 && rem >= 4) {
// All accesses of this kind are valid
WriteBufferValue<u32>(readBuf, readOffset, vgic.ReadGicdRegister(offset + readOffset, 4));
readOffset += 4;
rem -= 4;
} else if ((offset + readOffset) % 2 == 0 && rem >= 2) {
// All accesses of this kind would be translated to ldrh and are thus invalid. Abort.
return readOffset;
} else if (VirtualGic::ValidateGicdRegisterAccess(offset + readOffset, 1)) {
// Valid byte access
WriteBufferValue<u8>(readBuf, readOffset, vgic.ReadGicdRegister(offset + readOffset, 1));
readOffset += 1;
rem -= 1;
} else {
// Invalid byte access
return readOffset;
}
}
}
if (writeBuf != nullptr) {
size_t writeOffset = 0;
size_t rem = size;
while (rem > 0) {
if ((offset + writeOffset) % 4 == 0 && rem >= 4) {
// All accesses of this kind are valid
vgic.WriteGicdRegister(ReadBufferValue<u32>(writeBuf, writeOffset), offset + writeOffset, 4);
writeOffset += 4;
rem -= 4;
} else if ((offset + writeOffset) % 2 == 0 && rem >= 2) {
// All accesses of this kind would be translated to ldrh and are thus invalid. Abort.
return writeOffset;
} else if (VirtualGic::ValidateGicdRegisterAccess(offset + writeOffset, 1)) {
// Valid byte access
vgic.WriteGicdRegister(ReadBufferValue<u8>(writeBuf, writeOffset), offset + writeOffset, 1);
writeOffset += 1;
rem -= 1;
} else {
// Invalid byte access
return writeOffset;
}
}
}
return size;
}
size_t GuestReadWriteDeviceMemory(void *addr, size_t size, void *readBuf, const void *writeBuf)
{
if (readBuf != nullptr) {
size_t sz = SafeIoCopy(readBuf, addr, size);
if (sz < size) {
return sz;
}
}
if (writeBuf != nullptr) {
size_t sz = SafeIoCopy(addr, writeBuf, size);
if (sz < size) {
return sz;
}
}
// Translation tables must be on Normal memory & Device memory isn't cacheable, so we don't have
// that kind of thing to handle...
return size;
}
size_t GuestReadWriteNormalMemory(void *addr, size_t size, void *readBuf, const void *writeBuf)
{
if (readBuf != nullptr) {
std::memcpy(readBuf, addr, size);
}
if (writeBuf != nullptr) {
std::memcpy(addr, writeBuf, size);
// We may have written to executable memory or to translation tables...
// & the page may have various aliases.
// We need to ensure cache & TLB coherency.
CleanDataCacheRangePoU(addr, size);
u32 policy = GetInstructionCachePolicy();
if (policy == 1 || policy == 2) {
// AVIVT, VIVT
InvalidateInstructionCache();
} else {
// VPIPT, PIPT
// Ez coherency, just do range operations...
InvalidateInstructionCacheRangePoU(addr, size);
}
TlbInvalidateEl1();
dsb();
isb();
}
return size;
}
size_t GuestReadWriteMemoryPage(uintptr_t addr, size_t size, void *readBuf, const void *writeBuf)
{
InterruptMaskGuard ig{};
size_t offset = addr & 0xFFFul;
// Translate the VA, stages 1&2
__asm__ __volatile__ ("at s12e1r, %0" :: "r"(addr) : "memory");
u64 par = THERMOSPHERE_GET_SYSREG(par_el1);
if (par & PAR_F) {
// The translation failed. Why?
if (par & PAR_S) {
// Stage 2 fault. Could be an attempt to access the GICD, let's see what the IPA is...
__asm__ __volatile__ ("at s1e1r, %0" :: "r"(addr) : "memory");
par = THERMOSPHERE_GET_SYSREG(par_el1);
if ((par & PAR_F) != 0 || (par & PAR_PA_MASK) != VirtualGic::gicdPhysicalAddress) {
// The guest doesn't have access to it...
// Read as 0, write ignored
if (readBuf != NULL) {
std::memset(readBuf, 0, size);
}
} else {
// GICD mmio
size = GuestReadWriteGicd(offset, size, readBuf, writeBuf);
}
} else {
// Oops, couldn't read/write anything (stage 1 fault)
size = 0;
}
} else {
/*
Translation didn't fail.
To avoid "B2.8 Mismatched memory attributes" we must use the same effective
attributes & shareability as the guest.
Note that par_el1 reports the effective shareablity of device and noncacheable memory as inner shareable.
In fact, the VMSAv8-64 section in the Armv8 ARM reads:
"The shareability field is only relevant if the memory is a Normal Cacheable memory type. All Device and Normal
Non-cacheable memory regions are always treated as Outer Shareable, regardless of the translation table
shareability attributes."
There's one corner case where we can't avoid it: another core is running,
changes the attributes (other than permissions) of the page, and issues
a broadcasting TLB maintenance instructions and/or accesses the page with the altered
attribute itself. We don't handle this corner case -- just don't read/write that kind of memory...
*/
u64 memAttribs = (par >> PAR_ATTR_SHIFT) & PAR_ATTR_MASK;
u64 shrb = (par >> PAR_SH_SHIFT) & PAR_SH_MASK;
uintptr_t pa = par & PAR_PA_MASK;
uintptr_t va = MemoryMap::MapGuestPage(pa, memAttribs, shrb);
void *vaddr = reinterpret_cast<void *>(va + offset);
if (memAttribs & 0xF0) {
// Normal memory, or unpredictable
size = GuestReadWriteNormalMemory(vaddr, size, readBuf, writeBuf);
} else {
// Device memory, or unpredictable
size = GuestReadWriteDeviceMemory(vaddr, size, readBuf, writeBuf);
}
MemoryMap::UnmapGuestPage();
}
return size;
}
}
namespace ams::hvisor {
size_t GuestReadWriteMemory(uintptr_t addr, size_t size, void *readBuf, const void *writeBuf)
{
uintptr_t curAddr = addr;
size_t remainingAmount = size;
u8 *rb8 = reinterpret_cast<u8 *>(readBuf);
const u8 *wb8 = reinterpret_cast<const u8 *>(writeBuf);
while (remainingAmount > 0) {
size_t expectedAmount = ((curAddr & ~0xFFFul) + 0x1000) - curAddr;
expectedAmount = expectedAmount > remainingAmount ? remainingAmount : expectedAmount;
size_t actualAmount = GuestReadWriteMemoryPage(curAddr, expectedAmount, rb8, wb8);
curAddr += actualAmount;
rb8 += actualAmount;
wb8 += actualAmount;
remainingAmount -= actualAmount;
if (actualAmount != expectedAmount) {
break;
}
}
return curAddr - addr;
}
}