From: Ilias Apalodimas Date: Wed, 18 Jun 2025 06:58:13 +0000 (+0300) Subject: arm: io.h: Fix io accessors for KVM X-Git-Tag: v2025.10-rc1~91^2~14^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc512700ad46c16531ac57dbe5bba78d7153961d;p=pandora-u-boot.git arm: io.h: Fix io accessors for KVM commit 2e2c2a5e72a8 ("arm: qemu: override flash accessors to use virtualizable instructions") explains why we can't have instructions with multiple output registers when running under QEMU + KVM and the instruction leads to an exception to the hypervisor. USB XHCI is such a case (MMIO) where a ldr w1, [x0], #4 is emitted for xhci_start() which works fine with QEMU but crashes for QEMU + KVM. These instructions cannot be emulated by KVM as they do not produce syndrome information data that KVM can use to infer the destination register, the faulting address, whether it was a load or store, or if it's a 32 or 64 bit general-purpose register. As a result an external abort is injected from QEMU, via ext_dabt_pending to KVM and we end up throwing an exception that looks like U-Boot 2025.07-rc4 (Jun 10 2025 - 12:00:15 +0000) [...] Register 8001040 NbrPorts 8 Starting the controller "Synchronous Abort" handler, esr 0x96000010, far 0x10100040 elr: 000000000005b1c8 lr : 000000000005b1ac (reloc) elr: 00000000476fc1c8 lr : 00000000476fc1ac x0 : 0000000010100040 x1 : 0000000000000001 x2 : 0000000000000000 x3 : 0000000000003e80 x4 : 0000000000000000 x5 : 00000000477a5694 x6 : 0000000000000038 x7 : 000000004666f360 x8 : 0000000000000000 x9 : 00000000ffffffd8 x10: 000000000000000d x11: 0000000000000006 x12: 0000000046560a78 x13: 0000000046560dd0 x14: 00000000ffffffff x15: 000000004666eed2 x16: 00000000476ee2f0 x17: 0000000000000000 x18: 0000000046660dd0 x19: 000000004666f480 x20: 0000000000000000 x21: 0000000010100040 x22: 0000000010100000 x23: 0000000000000000 x24: 0000000000000000 x25: 0000000000000000 x26: 0000000000000000 x27: 0000000000000000 x28: 0000000000000000 x29: 000000004666f360 Code: d5033fbf aa1503e0 5287d003 52800002 (b8004401) Resetting CPU ... There are two problems making this the default. - It will emit ldr + add or str + add instead of ldr/str(post increment) in somne cases - Some platforms that depend on TPL/SPL grow in size enough so that the binary doesn't fit anymore. So let's add proper I/O accessors add a Kconfig option to turn it off by default apart from our QEMU builds. Reported-by: Mikko Rapeli Tested-by: Mikko Rapeli Signed-off-by: Ilias Apalodimas --- diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 6ff3f2750ea..f6430a5aaf0 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -108,6 +108,18 @@ config LNX_KRNL_IMG_TEXT_OFFSET_BASE The value subtracted from CONFIG_TEXT_BASE to calculate the TEXT_OFFSET value written to the Linux kernel image header. +config KVM_VIRT_INS + bool "Emit virtualizable instructions" + help + Instructions in the ARM ISA that have multiple output registers, + can't be used if the instruction leads to an exception to the hypervisor. + These instructions cannot be emulated by KVM because they do not produce + syndrome information data that KVM can use to infer the destination + register, the faulting address, whether it was a load or store, + if it's a 32 or 64 bit general-purpose register amongst other things. + Use this to produce virtualizable instructions if you plan to run U-Boot + with KVM. + config NVIC bool diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index 89b1015bc4d..85ec0e6937e 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -20,23 +20,108 @@ static inline void sync(void) { } -/* Generic virtual read/write. */ -#define __arch_getb(a) (*(volatile unsigned char *)(a)) -#define __arch_getw(a) (*(volatile unsigned short *)(a)) -#define __arch_getl(a) (*(volatile unsigned int *)(a)) -#define __arch_getq(a) (*(volatile unsigned long long *)(a)) +#ifdef CONFIG_ARM64 +#define __W "w" +#else +#define __W +#endif + +#if CONFIG_IS_ENABLED(SYS_THUMB_BUILD) +#define __R "l" +#define __RM "=l" +#else +#define __R "r" +#define __RM "=r" +#endif -#define __arch_putb(v,a) (*(volatile unsigned char *)(a) = (v)) -#define __arch_putw(v,a) (*(volatile unsigned short *)(a) = (v)) -#define __arch_putl(v,a) (*(volatile unsigned int *)(a) = (v)) -#define __arch_putq(v,a) (*(volatile unsigned long long *)(a) = (v)) +#ifdef CONFIG_KVM_VIRT_INS +/* + * The __raw_writeX/__raw_readX below should be converted to static inline + * functions. However doing so produces a lot of compilation warnings when + * called with a raw address. Convert these once the callers have been fixed. + */ +#define __raw_writeb(val, addr) \ + do { \ + asm volatile("strb %" __W "0, [%1]" \ + : \ + : __R ((u8)(val)), __R (addr)); \ + } while (0) + +#define __raw_readb(addr) \ + ({ \ + u32 __val; \ + asm volatile("ldrb %" __W "0, [%1]" \ + : __RM (__val) \ + : __R (addr)); \ + __val; \ + }) + +#define __raw_writew(val, addr) \ + do { \ + asm volatile("strh %" __W "0, [%1]" \ + : \ + : __R ((u16)(val)), __R (addr)); \ + } while (0) + +#define __raw_readw(addr) \ + ({ \ + u32 __val; \ + asm volatile("ldrh %" __W "0, [%1]" \ + : __RM (__val) \ + : __R (addr)); \ + __val; \ + }) + +#define __raw_writel(val, addr) \ + do { \ + asm volatile("str %" __W "0, [%1]" \ + : \ + : __R ((u32)(val)), __R (addr)); \ + } while (0) + +#define __raw_readl(addr) \ + ({ \ + u32 __val; \ + asm volatile("ldr %" __W "0, [%1]" \ + : __RM (__val) \ + : __R (addr)); \ + __val; \ + }) + +#define __raw_writeq(val, addr) \ + do { \ + asm volatile("str %0, [%1]" \ + : \ + : __R ((u64)(val)), __R (addr)); \ + } while (0) + +#define __raw_readq(addr) \ + ({ \ + u64 __val; \ + asm volatile("ldr %0, [%1]" \ + : __RM (__val) \ + : __R (addr)); \ + __val; \ + }) +#else +/* Generic virtual read/write. */ +#define __raw_readb(a) (*(volatile unsigned char *)(a)) +#define __raw_readw(a) (*(volatile unsigned short *)(a)) +#define __raw_readl(a) (*(volatile unsigned int *)(a)) +#define __raw_readq(a) (*(volatile unsigned long long *)(a)) + +#define __raw_writeb(v, a) (*(volatile unsigned char *)(a) = (v)) +#define __raw_writew(v, a) (*(volatile unsigned short *)(a) = (v)) +#define __raw_writel(v, a) (*(volatile unsigned int *)(a) = (v)) +#define __raw_writeq(v, a) (*(volatile unsigned long long *)(a) = (v)) +#endif static inline void __raw_writesb(unsigned long addr, const void *data, int bytelen) { uint8_t *buf = (uint8_t *)data; while(bytelen--) - __arch_putb(*buf++, addr); + __raw_writeb(*buf++, addr); } static inline void __raw_writesw(unsigned long addr, const void *data, @@ -44,7 +129,7 @@ static inline void __raw_writesw(unsigned long addr, const void *data, { uint16_t *buf = (uint16_t *)data; while(wordlen--) - __arch_putw(*buf++, addr); + __raw_writew(*buf++, addr); } static inline void __raw_writesl(unsigned long addr, const void *data, @@ -52,40 +137,30 @@ static inline void __raw_writesl(unsigned long addr, const void *data, { uint32_t *buf = (uint32_t *)data; while(longlen--) - __arch_putl(*buf++, addr); + __raw_writel(*buf++, addr); } static inline void __raw_readsb(unsigned long addr, void *data, int bytelen) { uint8_t *buf = (uint8_t *)data; while(bytelen--) - *buf++ = __arch_getb(addr); + *buf++ = __raw_readb(addr); } static inline void __raw_readsw(unsigned long addr, void *data, int wordlen) { uint16_t *buf = (uint16_t *)data; while(wordlen--) - *buf++ = __arch_getw(addr); + *buf++ = __raw_readw(addr); } static inline void __raw_readsl(unsigned long addr, void *data, int longlen) { uint32_t *buf = (uint32_t *)data; while(longlen--) - *buf++ = __arch_getl(addr); + *buf++ = __raw_readl(addr); } -#define __raw_writeb(v,a) __arch_putb(v,a) -#define __raw_writew(v,a) __arch_putw(v,a) -#define __raw_writel(v,a) __arch_putl(v,a) -#define __raw_writeq(v,a) __arch_putq(v,a) - -#define __raw_readb(a) __arch_getb(a) -#define __raw_readw(a) __arch_getw(a) -#define __raw_readl(a) __arch_getl(a) -#define __raw_readq(a) __arch_getq(a) - /* * TODO: The kernel offers some more advanced versions of barriers, it might * have some advantages to use them instead of the simple one here. @@ -98,15 +173,15 @@ static inline void __raw_readsl(unsigned long addr, void *data, int longlen) #define smp_processor_id() 0 -#define writeb(v,c) ({ u8 __v = v; __iowmb(); __arch_putb(__v,c); __v; }) -#define writew(v,c) ({ u16 __v = v; __iowmb(); __arch_putw(__v,c); __v; }) -#define writel(v,c) ({ u32 __v = v; __iowmb(); __arch_putl(__v,c); __v; }) -#define writeq(v,c) ({ u64 __v = v; __iowmb(); __arch_putq(__v,c); __v; }) +#define writeb(v, c) ({ u8 __v = v; __iowmb(); writeb_relaxed(__v, c); __v; }) +#define writew(v, c) ({ u16 __v = v; __iowmb(); writew_relaxed(__v, c); __v; }) +#define writel(v, c) ({ u32 __v = v; __iowmb(); writel_relaxed(__v, c); __v; }) +#define writeq(v, c) ({ u64 __v = v; __iowmb(); writeq_relaxed(__v, c); __v; }) -#define readb(c) ({ u8 __v = __arch_getb(c); __iormb(); __v; }) -#define readw(c) ({ u16 __v = __arch_getw(c); __iormb(); __v; }) -#define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; }) -#define readq(c) ({ u64 __v = __arch_getq(c); __iormb(); __v; }) +#define readb(c) ({ u8 __v = readb_relaxed(c); __iormb(); __v; }) +#define readw(c) ({ u16 __v = readw_relaxed(c); __iormb(); __v; }) +#define readl(c) ({ u32 __v = readl_relaxed(c); __iormb(); __v; }) +#define readq(c) ({ u64 __v = readq_relaxed(c); __iormb(); __v; }) /* * Relaxed I/O memory access primitives. These follow the Device memory @@ -121,13 +196,10 @@ static inline void __raw_readsl(unsigned long addr, void *data, int longlen) #define readq_relaxed(c) ({ u64 __r = le64_to_cpu((__force __le64) \ __raw_readq(c)); __r; }) -#define writeb_relaxed(v, c) ((void)__raw_writeb((v), (c))) -#define writew_relaxed(v, c) ((void)__raw_writew((__force u16) \ - cpu_to_le16(v), (c))) -#define writel_relaxed(v, c) ((void)__raw_writel((__force u32) \ - cpu_to_le32(v), (c))) -#define writeq_relaxed(v, c) ((void)__raw_writeq((__force u64) \ - cpu_to_le64(v), (c))) +#define writeb_relaxed(v, c) __raw_writeb((v), (c)) +#define writew_relaxed(v, c) __raw_writew((__force u16)cpu_to_le16(v), (c)) +#define writel_relaxed(v, c) __raw_writel((__force u32)cpu_to_le32(v), (c)) +#define writeq_relaxed(v, c) __raw_writeq((__force u64)cpu_to_le64(v), (c)) /* * The compiler seems to be incapable of optimising constants