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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 1/4] xen/io: provide helpers for multi size MMIO accesses
On Tue, Apr 15, 2025 at 05:32:43PM +0200, Roger Pau Monne wrote:
> Several handlers have the same necessity of reading or writing from or to
> an MMIO region using 1, 2, 4 or 8 bytes accesses. So far this has been
> open-coded in the function itself. Instead provide a new set of handlers
> that encapsulate the accesses.
>
> Since the added helpers are not architecture specific, introduce a new
> generic io.h header.
>
> No functional change intended.
>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Denis Mukhin <dmukhin@xxxxxxxx>
> ---
> Changes since v1:
> - Limit {read,write}q() to 64bit architectures.
> - Always have a default case in switch statement.
> ---
> xen/arch/x86/hvm/vmsi.c | 47 ++--------------------------
> xen/arch/x86/mm.c | 32 +++++--------------
> xen/drivers/vpci/msix.c | 47 ++--------------------------
> xen/include/xen/io.h | 68 +++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 81 insertions(+), 113 deletions(-)
> create mode 100644 xen/include/xen/io.h
>
> diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c
> index fd83abb929ec..61b89834d97d 100644
> --- a/xen/arch/x86/hvm/vmsi.c
> +++ b/xen/arch/x86/hvm/vmsi.c
> @@ -24,6 +24,7 @@
> * Will be merged it with virtual IOAPIC logic, since most is the same
> */
>
> +#include <xen/io.h>
> #include <xen/types.h>
> #include <xen/mm.h>
> #include <xen/xmalloc.h>
> @@ -304,28 +305,7 @@ static void adjacent_read(
>
> hwaddr = fix_to_virt(fixmap_idx) + PAGE_OFFSET(address);
>
> - switch ( len )
> - {
> - case 1:
> - *pval = readb(hwaddr);
> - break;
> -
> - case 2:
> - *pval = readw(hwaddr);
> - break;
> -
> - case 4:
> - *pval = readl(hwaddr);
> - break;
> -
> - case 8:
> - *pval = readq(hwaddr);
> - break;
> -
> - default:
> - ASSERT_UNREACHABLE();
> - break;
> - }
> + *pval = read_mmio(hwaddr, len);
> }
>
> static void adjacent_write(
> @@ -344,28 +324,7 @@ static void adjacent_write(
>
> hwaddr = fix_to_virt(fixmap_idx) + PAGE_OFFSET(address);
>
> - switch ( len )
> - {
> - case 1:
> - writeb(val, hwaddr);
> - break;
> -
> - case 2:
> - writew(val, hwaddr);
> - break;
> -
> - case 4:
> - writel(val, hwaddr);
> - break;
> -
> - case 8:
> - writeq(val, hwaddr);
> - break;
> -
> - default:
> - ASSERT_UNREACHABLE();
> - break;
> - }
> + write_mmio(hwaddr, val, len);
> }
>
> static int cf_check msixtbl_read(
> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
> index 1cf236516789..989e62e7ce6f 100644
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -95,6 +95,7 @@
> #include <xen/guest_access.h>
> #include <xen/hypercall.h>
> #include <xen/init.h>
> +#include <xen/io.h>
> #include <xen/iocap.h>
> #include <xen/ioreq.h>
> #include <xen/irq.h>
> @@ -116,7 +117,6 @@
> #include <asm/flushtlb.h>
> #include <asm/guest.h>
> #include <asm/idt.h>
> -#include <asm/io.h>
> #include <asm/io_apic.h>
> #include <asm/ldt.h>
> #include <asm/mem_sharing.h>
> @@ -5102,7 +5102,7 @@ static void __iomem *subpage_mmio_map_page(
> static void subpage_mmio_write_emulate(
> mfn_t mfn,
> unsigned int offset,
> - const void *data,
> + unsigned long data,
> unsigned int len)
> {
> struct subpage_ro_range *entry;
> @@ -5115,7 +5115,6 @@ static void subpage_mmio_write_emulate(
>
> if ( test_bit(offset / MMIO_RO_SUBPAGE_GRAN, entry->ro_elems) )
> {
> - write_ignored:
> gprintk(XENLOG_WARNING,
> "ignoring write to R/O MMIO 0x%"PRI_mfn"%03x len %u\n",
> mfn_x(mfn), offset, len);
> @@ -5131,26 +5130,7 @@ static void subpage_mmio_write_emulate(
> return;
> }
>
> - addr += offset;
> - switch ( len )
> - {
> - case 1:
> - writeb(*(const uint8_t*)data, addr);
> - break;
> - case 2:
> - writew(*(const uint16_t*)data, addr);
> - break;
> - case 4:
> - writel(*(const uint32_t*)data, addr);
> - break;
> - case 8:
> - writeq(*(const uint64_t*)data, addr);
> - break;
> - default:
> - /* mmio_ro_emulated_write() already validated the size */
> - ASSERT_UNREACHABLE();
> - goto write_ignored;
> - }
> + write_mmio(addr + offset, data, len);
> }
>
> #ifdef CONFIG_HVM
> @@ -5185,18 +5165,20 @@ int cf_check mmio_ro_emulated_write(
> struct x86_emulate_ctxt *ctxt)
> {
> struct mmio_ro_emulate_ctxt *mmio_ro_ctxt = ctxt->data;
> + unsigned long data = 0;
>
> /* Only allow naturally-aligned stores at the original %cr2 address. */
> if ( ((bytes | offset) & (bytes - 1)) || !bytes ||
> - offset != mmio_ro_ctxt->cr2 )
> + offset != mmio_ro_ctxt->cr2 || bytes > sizeof(data) )
> {
> gdprintk(XENLOG_WARNING, "bad access (cr2=%lx, addr=%lx,
> bytes=%u)\n",
> mmio_ro_ctxt->cr2, offset, bytes);
> return X86EMUL_UNHANDLEABLE;
> }
>
> + memcpy(&data, p_data, bytes);
> subpage_mmio_write_emulate(mmio_ro_ctxt->mfn, PAGE_OFFSET(offset),
> - p_data, bytes);
> + data, bytes);
>
> return X86EMUL_OKAY;
> }
> diff --git a/xen/drivers/vpci/msix.c b/xen/drivers/vpci/msix.c
> index 6bd8c55bb48e..6455f2a03a01 100644
> --- a/xen/drivers/vpci/msix.c
> +++ b/xen/drivers/vpci/msix.c
> @@ -17,6 +17,7 @@
> * License along with this program; If not, see
> <http://www.gnu.org/licenses/>.
> */
>
> +#include <xen/io.h>
> #include <xen/sched.h>
> #include <xen/vpci.h>
>
> @@ -344,28 +345,7 @@ static int adjacent_read(const struct domain *d, const
> struct vpci_msix *msix,
> return X86EMUL_OKAY;
> }
>
> - switch ( len )
> - {
> - case 1:
> - *data = readb(mem + PAGE_OFFSET(addr));
> - break;
> -
> - case 2:
> - *data = readw(mem + PAGE_OFFSET(addr));
> - break;
> -
> - case 4:
> - *data = readl(mem + PAGE_OFFSET(addr));
> - break;
> -
> - case 8:
> - *data = readq(mem + PAGE_OFFSET(addr));
> - break;
> -
> - default:
> - ASSERT_UNREACHABLE();
> - break;
> - }
> + *data = read_mmio(mem + PAGE_OFFSET(addr), len);
> spin_unlock(&vpci->lock);
>
> return X86EMUL_OKAY;
> @@ -493,28 +473,7 @@ static int adjacent_write(const struct domain *d, const
> struct vpci_msix *msix,
> return X86EMUL_OKAY;
> }
>
> - switch ( len )
> - {
> - case 1:
> - writeb(data, mem + PAGE_OFFSET(addr));
> - break;
> -
> - case 2:
> - writew(data, mem + PAGE_OFFSET(addr));
> - break;
> -
> - case 4:
> - writel(data, mem + PAGE_OFFSET(addr));
> - break;
> -
> - case 8:
> - writeq(data, mem + PAGE_OFFSET(addr));
> - break;
> -
> - default:
> - ASSERT_UNREACHABLE();
> - break;
> - }
> + write_mmio(mem + PAGE_OFFSET(addr), data, len);
> spin_unlock(&vpci->lock);
>
> return X86EMUL_OKAY;
> diff --git a/xen/include/xen/io.h b/xen/include/xen/io.h
> new file mode 100644
> index 000000000000..4495a04c403e
> --- /dev/null
> +++ b/xen/include/xen/io.h
> @@ -0,0 +1,68 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * IO related routines.
> + *
> + * Copyright (c) 2025 Cloud Software Group
> + */
> +#ifndef XEN_IO_H
> +#define XEN_IO_H
> +
> +#include <xen/bug.h>
> +
> +#include <asm/io.h>
> +
> +static inline unsigned long read_mmio(const volatile void __iomem *mem,
> + unsigned int size)
> +{
> + switch ( size )
> + {
> + case 1:
> + return readb(mem);
> +
> + case 2:
> + return readw(mem);
> +
> + case 4:
> + return readl(mem);
> +
> +#ifdef CONFIG_64BIT
> + case 8:
> + return readq(mem);
> +#endif
> +
> + default:
> + ASSERT_UNREACHABLE();
> + return ~0UL;
> + }
> +}
> +
> +static inline void write_mmio(volatile void __iomem *mem, unsigned long data,
> + unsigned int size)
> +{
> + switch ( size )
> + {
> + case 1:
> + writeb(data, mem);
> + break;
> +
> + case 2:
> + writew(data, mem);
> + break;
> +
> + case 4:
> + writel(data, mem);
> + break;
> +
> +#ifdef CONFIG_64BIT
> + case 8:
> + writeq(data, mem);
> + break;
> +#endif
> +
> + default:
> + ASSERT_UNREACHABLE();
> + break;
> + }
> +}
> +
> +#endif /* XEN_IO_H */
> --
> 2.48.1
>
>
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